Cast from Hit Point Systems?

[TechnOkami]

So, I've been putting it upon myself to slowly but surely make a true, powerful, and fun to play Blood Mage base class. My question is simple: are there any systems which utilize a "cast from hit points" system to sling their spells?

[Jjeinn-tae]

If you're willing to wait ~three years, I'll be able to get mine out. :smalltongue:

Of course, since you really want something that'll be helpful to you now; I'm pretty sure I've seen some alternate rules for D&D3.5 with that sort of thing. I know there's a couple base classes based around that on here, but I think I saw a "Magic has a cost" sort of thing for spellcasters around here. I'll see if I can find it.

[Kellus]

Hit points seem like they would be a good resource to spend in spellcasting, but in reality they're one of the worst ones you could think of. The problem is that hit points are a binary thing: either you have some or you don't. When you don't, you're dead. Until that point you can continue to fight at 100% effectiveness. Having characters actually die on a regular basis in the campaign is a pretty bad thing most of the time. Aside from vindictive and stupid DMs, most PC deaths are the result of bad dice rolling. Which is totally OK in a TTRPG. But by giving the player the option to spend hit points to do 'stuff', you're encouraging suicide nova behaviour which forces the DM to either kill off the character or play with kid gloves.

Basically it's a bad currency to use for magic, because there's no downside to exploding all of your hit points as spells right up until you're actually dead. And the game becomes way less fun when you actually die.

Not to mention it makes the five minute workday even worse.

[TechnOkami]

True... which is why my version of the blood mage will have lots of self healing buffs, abilities, and hopefully, mechanics to provide for this sort of thing. I basically am trying to make a Blood Mage that can stay on its feet, and wont necessarily die after the first few spells cast.

Also, fluffwise, blood mages just sound cool.

[Kellus]

I'm not saying it can't be done, but you're going to waste a lot of space trying to prevent the problems that inevitably show up in play when hit points become a spendable resource. Blood mages are an awesome idea, but there's usually a better way to implement it mechanically (for example, making Fortitude saves to avoid a detrimental temporarily condition).

Another weird thing about a hit point based spellcaster is that they suddenly get much more awesome when there's a cleric in the party. Which makes it almost impossible to balance the class and magic system on its own merits.

[TechnOkami]

True... but if you make it so that the Blood Mage can only be healed by is own abilities and not those of external sources...

[Xefas]

MAID does this some. Their "Hit Point" stat is "Stress". Taking hits in combat increases your Stress, but many special abilities (such as Super Evasion, Trespass, and Lie Detector - which you could equate to magic) also cause Stress. If you're at a high Stress level, pushing your luck has to be a calculated decision.

Kobolds Ate My Baby sort of does this. Every time you cast a spell, you gain a Horrible Kobold Death Check and have to roll to see if you suffer Horrible Kobold Death upon the Horrible Kobold Death Table.

Horrible Kobold Death Checks are more or less the "Hit Points" of the game. Your Kobold actually has a "Hit Point"esque stat, IIRC, but being a Kobold, it's so low, that if you get into a fight with anything bigger than a chicken, you're going to die anyway. So, the proper management of the more powerful special abilities and spells, which tack on more and more Horrible Kobold Death Checks, is the primary way to survive.

[TechnOkami]

Horrible Kobold Death Checks are more or less the "Hit Points" of the game. Your Kobold actually has a "Hit Point"esque stat, IIRC, but being a Kobold, it's so low, that if you get into a fight with anything bigger than a chicken, you're going to die anyway. So, the proper management of the more powerful special abilities and spells, which tack on more and more Horrible Kobold Death Checks, is the primary way to survive.

That sounds amusing... :smallbiggrin:

[Kellus]

True... but if you make it so that the Blood Mage can only be healed by is own abilities and not those of external sources...

That's a really bad idea. I would strongly advise against introducing a dissociated mechanic like requiring "super healing" for a character that takes levels in this class. The whole point of the cure light wounds spell is that it heals you. If you introduce something like that, the player with the cleric will be unhappy because he arbitrarily can't use his class features properly and the player with the blood mage will be unhappy because they can't be healed properly like they could before they multiclassed into blood mage. Nobody wins in that scenario.

Think of it this way: by making the blood mage require Super Healing in order to heal, you've fundamentally changed how he interacts with the game world. Which means you need to make a lot of other decisions too. For example:

• Does the blood mage take damage from negative energy.
• Does a blood mage with Tomb Tained Soul gain health from negative energy.
• Is a blood mage immune to the deadly effects of the Positive Energy Plane.
• Does a blood mage heal with a good night's sleep.
• Can a blood mage recover from disease.
• Can a blood mage receive magical effects to cure diseases and poisons.
• Can a blood mage multiclassed as a crusader use maneuvers that restore hit points.

These are only a few of the things that are going to come up when you make such a far-reaching change to the way the character interacts with the rules. I think the blood mage is a cool idea, but this is a bad way to go about it.

[TechnOkami]

• Does the blood mage take damage from negative energy.
• Does a blood mage with Tomb Tained Soul gain health from negative energy.
• Is a blood mage immune to the deadly effects of the Positive Energy Plane.
• Does a blood mage heal with a good night's sleep.
• Can a blood mage recover from disease.
• Can a blood mage receive magical effects to cure diseases and poisons.
• Can a blood mage multiclassed as a crusader use maneuvers that restore hit points.

-yes
-no
-no
-yes
-yes
-yes
-no

Yes, I see what you mean, and honestly I think it can be done without making it completely broken, in either sense of the word.

[cattoy]

The Fantasy Trip aka Gurps, 0th edition had magic that was powered by, essentially, HP.

[Velaryon]

Star Wars d20, both the original and Revised Core Rules, used hit points to power Force powers. But when WotC came out with Saga edition, they (wisely IMO) abandoned that model.

[CodeRed]

There are two things I can think of to give you some ideas:

1. In League of Legends, my current DoTA-clone du jour, there is a hero you can play called Vladimir who is a potent blood magus. All of his spells are powered off his own hitpoints which would seem terrible in such a pvp game. Each of his four abilities is triggered by taking away a certain percentage of his hitpoints but 3 out of the 4 either heal him or increase his health regeneration rate based on the damage done. I would propose that for a blood mage you do something similar.

For example, a spell could cost a number of lifepoints equivalent to the power point conversion of psionic powers by level: 1st- 1, 2nd- 3, 3rd- 5, 4th- 7 and so on up to ninth. If the spell deals damage, make it so that it automatically leeches back half of its cost if it deals at least one point of damage to an enemy (minimum 1). Keep the hitpoint cost the same for all other spells but make them grant the caster Fast Healing = half the lvl of the spell rounded down with a minimum of 1 for an equal number of rounds. (Blood Mage 3 casts a Scorching Ray for 3 hp, if it hits and damages at least one target, he gets 1 hp back.) (Blood Mage 17 casts Time Stop for 17 hp and gets Fast Healing 4 for 4 rounds.) This builds in an automatic opportunity cost as yes, the Blood Mage will heal back a good bit of the damage he deals to himself but he doesn't get it until the start of his next turn for buff spells or non-damaging spells. Let the Fast Healings stack and not override as that's the main mechanic of the class. Sure, you can spam spell after spell but the limit is that if you bring yourself too low, you can far more be easily killed off before you get that healing next round. As well, for damaging spells, your investing that hp beforehand so if you miss or everyone you target makes their Reflex with Evasion, your spending far more hp for that spell then normal. (I get that the class can effectively spam lvl 1 spells but once again, the Fast Healing doesn't heal until their next turn. As to the damaging lvl 1s, yes they can spam them but only as long as they damage someone with it, so don't put Magic Missile on its spell list then :P ) As for metamagic, let them use it as any other mage would. Find the modified spell level, pay the hp cost for that level and then deal with its effects, either straight hp gain back if it damages or FH if it doesn't.

As to the Cleric making this overpowered? Let him spend spell slots. At that point its pretty much a fair exchange spell slot for spell slot from a Tier 1 to a Tier whatever this supposed Blood Mage would be. I'd be far more worried about the Cleric using those slots for something far more powerful (doing damage or preventing damage is almost always more effective then after the effect healing). To prevent too much Fast Healing abuse, make it so the Blood Mage can either take his stacking Fast Healing from casting spells or the traditional rule of only one source from any other source he is affected with at the start of his turn.

Idk, it is really early and I got far more involved in this than I thought I would lol. If you suffered through that wall of text, I am humbled.

2. Take a look at these: The Limit Warriors (http://community.wizards.com/go/thread/view/75882/19528498/The_Limit_Warriors?pg=1)

These are some really cool Homebrew classes based off FF7's main characters and their ability to use Limit Breaks. Simply, the more damage they take, the more abilities they can pull out of their hat. The Limit Mage for example essentially uses the spell slots to power point conversion suggested in the Expanded Psionics Handbook and starts the day with a spell pool equal to their level times ten. However, as they cast spells this is depleted based on the spell level (he shows this in the Limit Point Costs s-block). However, as the Mage takes damage, the equivalent amount of damage is added back into their spell pool at a 1:1 ratio up to their max (that lvl x 10 again). It is sort of a reverse Blood Mage in that you can fuel damage taken into power but with some refluffing could work well enough I think.

TL;DR? Too damn bad, no simple explanations here. :P

Edit: Just realized I assumed that this was in the 3.5 Forum when's it the Roleplay General Forum. My bad. All assumptions and descriptions above are based on 3.5.

[TechnOkami]

There are two things I can think of to give you some ideas:

1. In League of Legends, my current DoTA-clone du jour, there is a hero you can play called Vladimir who is a potent blood magus. All of his spells are powered off his own hitpoints which would seem terrible in such a pvp game. Each of his four abilities is triggered by taking away a certain percentage of his hitpoints but 3 out of the 4 either heal him or increase his health regeneration rate based on the damage done. I would propose that for a blood mage you do something similar.

For example, a spell could cost a number of lifepoints equivalent to the power point conversion of psionic powers by level: 1st- 1, 2nd- 3, 3rd- 5, 4th- 7 and so on up to ninth. If the spell deals damage, make it so that it automatically leeches back half of its cost if it deals at least one point of damage to an enemy (minimum 1). Keep the hitpoint cost the same for all other spells but make them grant the caster Fast Healing = half the lvl of the spell rounded down with a minimum of 1 for an equal number of rounds. (Blood Mage 3 casts a Scorching Ray for 3 hp, if it hits and damages at least one target, he gets 1 hp back.) (Blood Mage 17 casts Time Stop for 17 hp and gets Fast Healing 4 for 4 rounds.) This builds in an automatic opportunity cost as yes, the Blood Mage will heal back a good bit of the damage he deals to himself but he doesn't get it until the start of his next turn for buff spells or non-damaging spells. Let the Fast Healings stack and not override as that's the main mechanic of the class. Sure, you can spam spell after spell but the limit is that if you bring yourself too low, you can far more be easily killed off before you get that healing next round. As well, for damaging spells, your investing that hp beforehand so if you miss or everyone you target makes their Reflex with Evasion, your spending far more hp for that spell then normal. (I get that the class can effectively spam lvl 1 spells but once again, the Fast Healing doesn't heal until their next turn. As to the damaging lvl 1s, yes they can spam them but only as long as they damage someone with it, so don't put Magic Missile on its spell list then :P ) As for metamagic, let them use it as any other mage would. Find the modified spell level, pay the hp cost for that level and then deal with its effects, either straight hp gain back if it damages or FH if it doesn't.

As to the Cleric making this overpowered? Let him spend spell slots. At that point its pretty much a fair exchange spell slot for spell slot from a Tier 1 to a Tier whatever this supposed Blood Mage would be. I'd be far more worried about the Cleric using those slots for something far more powerful (doing damage or preventing damage is almost always more effective then after the effect healing). To prevent too much Fast Healing abuse, make it so the Blood Mage can either take his stacking Fast Healing from casting spells or the traditional rule of only one source from any other source he is affected with at the start of his turn.

Idk, it is really early and I got far more involved in this than I thought I would lol. If you suffered through that wall of text, I am humbled.

2. Take a look at these: The Limit Warriors (http://community.wizards.com/go/thread/view/75882/19528498/The_Limit_Warriors?pg=1)

These are some really cool Homebrew classes based off FF7's main characters and their ability to use Limit Breaks. Simply, the more damage they take, the more abilities they can pull out of their hat. The Limit Mage for example essentially uses the spell slots to power point conversion suggested in the Expanded Psionics Handbook and starts the day with a spell pool equal to their level times ten. However, as they cast spells this is depleted based on the spell level (he shows this in the Limit Point Costs s-block). However, as the Mage takes damage, the equivalent amount of damage is added back into their spell pool at a 1:1 ratio up to their max (that lvl x 10 again). It is sort of a reverse Blood Mage in that you can fuel damage taken into power but with some refluffing could work well enough I think.

TL;DR? Too damn bad, no simple explanations here. :P

...ok, I've got a lot to say.

1.) Your idea for casting hit points in that way is something I actually considered (power points now being hit points and all), and the way which you presented it sounds like it would actually work... I might just have to use that for the fundamentals of the class.

2.) A la the Cleric, I am still going to hold true that a blood mage cannot be healed by any external sources (with a crap-ton of detail to clearly explain what this means). If anything, it gives the feeling that the class isn't as broken as it can be.

3.) I really like the limit classes, 'nuff said. A mechanic like that isn't how I envision the Blood Mage, but I still like the classes nonetheless.

[CodeRed]

...ok, I've got a lot to say.

1.) Your idea for casting hit points in that way is something I actually considered (power points now being hit points and all), and the way which you presented it sounds like it would actually work... I might just have to use that for the fundamentals of the class.

2.) A la the Cleric, I am still going to hold true that a blood mage cannot be healed by any external sources (with a crap-ton of detail to clearly explain what this means). If anything, it gives the feeling that the class isn't as broken as it can be.

3.) I really like the limit classes, 'nuff said. A mechanic like that isn't how I envision the Blood Mage, but I still like the classes nonetheless.

Coolio. The idea of HP as PP just sort of came to me and then I though about the LoL hero I mentioned and it just kinda worked. If that's the route you end up going, I'd love to see the eventual class all worked out.

[TechnOkami]

Coolio. The idea of HP as PP just sort of came to me and then I though about the LoL hero I mentioned and it just kinda worked. If that's the route you end up going, I'd love to see the eventual class all worked out.

Random note: I play LoL, and use Vlad a lot :P

[Zale]

Why not just take slow-healing nonlethal damage? :smallconfused:

[TechnOkami]

Why not just take slow-healing nonlethal damage? :smallconfused:

Shot Answer: its annoying.

Long Answer: it doesn't fulfill the same meaning as having your valuable and precious hit points sacrificed to use spells. It would be like beating yourself over the head every time you wanted to cast something... its just better fluff-wise if actual hit points are lost.

[Aricandor]

Something I did when I wrote a blood magic school for another game was to make you able to cast the spells you knew "normally", at will and at no cost, or you could sacrifice some hit points to make the spells more powerful.

If the spell fizzled or failed to have effect (all targets resist it, you miss your attack roll for a ray-type thing...) it would not take those hit points.
There is of course some systems dissonance to deal with here, but I felt overall the basic principle worked out well, in that since hit points are ultimately a precious resource in a way that spell slots (or spell points or whatever the system uses) aren't, as much as possible of its use has to be put in the hands of the player.

You could make it more unforgiving, obviously, but it would likely get a lot less appealing to players.

[Leon]

Can a Blood mage use another's blood to do the work?

[RndmNumGen]

There is another system I've seen where a caster would normally cast spells from his mana points, but when he runs out, has the option to 'exhaust' himself and cast from HP - at a 125% increase - if he desperately needs to cast a spell. I don't really think this would work for what you're planning, but it's something to think about.

As far as not being able to healed my normal healing magic, I don't think allowing the blood mage to be healed is that big of a problem; HP is a resource like anything else, and if the Cleric is spending spell slots to keep the Blood Mage healed, the party's overall resources are still being depleted. The only real issue I see with this is that if you have an external source of healing, such as a Wand of Cure Light Wounds, you are converting a fixed resource into whatever spells you want to cast.

Even then, if the classes' whole shtick is sacrificing their own health to flexibly cast or empower magic when it is most needed, this shouldn't be a large problem, since that's what the class simply does.

If you really don't like the idea of a Blood Mage being able to receive full benefits of healing spells, consider maybe allowing them to be healed for half health. Then normal healing is still inefficient, but if the party stumbles along some situation where the Blood Mage is in desperate need of healing, such as if he's bleeding out, somebody else can still stabilize him by pouring a potion of CLW down his throat.

[LibraryOgre]

If I were to do this in 3.x, I'd probably go with spells doing non-lethal damage, and requiring a save to avoid becoming fatigued. Say, spells do twice their level in nonlethal, and you have to make a Fort save vs. 10 + spell's nonlethal damage to avoid becoming fatigued.

You might also go with save v. 10 + spell's non-lethal, with a save for half, but I think that doesn't adequately limit spellcasters, and makes spellcasting a "Up or Out" proposition; you don't really model the "I need to rest" aspect of fantasy novels.

[Arbitrarious]

Perhaps the class could have an extremely low HD like d2 or 1 and gains a pool of temp HP. This temp hp is used to cast spells. Normal spells can't replace temp HP and since temp HP from diff sources doesn't stack only temp HP gained by their class abilites would be able to refill their pool. This gives them a health buffer of real HP that can be healed so you can't cast to death. Reasoning "once your life is that weakened you blood lacks the potency needed" or something.

[Seb Wiers]

My question is simple: are there any systems which utilize a "cast from hit points" system to sling their spells?

Earthdawn: using certain talents causes (small amounts) of damage. Spellcasting can cause you a fair bit of damage if you try to use more power than your talents can handle. You can inflict self harm to push your talents.

Shadowrun: any spellcasting potentially causes fatigue (rapidly healed damage). You can "overcast" to put out more powerful versions of spells you know, at the risk of taking actual physical damage rather than fatigue. Certain mages can do sacrifice magic, inflicting dmage on themselves or helpless victims to help power spells.

Harnmaster: pretty much all magic use causes fatigue (same effects as injury, easier to heal). If you botch your spellcasting, its pretty likely you will take physical damage from the spell backfiring. It would be entirely possible to design spells that empower your other spellcasting at the expense of physical damage (or other detrimental self effects); similar magic exists already, but tends to trade increased casting time / complexity / requirements (rather than simple self harm) for increased power.

Call of Cthulu: um, sure. Just LEARNING magic is dangerous enough.


I actually think most of the games I've played support a self-harm / magic power trade. D&D is one of the only ones I've played that does NOT.

[Gadora]

Star Wars d20, both the original and Revised Core Rules, used hit points to power Force powers. But when WotC came out with Saga edition, they (wisely IMO) abandoned that model.

I happen to actually like those mechanics. I just think they're a horrible way to represent the Force. *Insert long rant on how quality of Star Wars stuff has dropped in 'recent' times* Then get off my lawn.

[Knaight]

There are plenty of systems wherein casting -particularly failed casting- injures the caster. This may not be a hit point system per se, as the mechanics of "hit points" aren't being used as much in newer games. As for these systems, the obvious ones include the Dresden Files RPG, which has a well liked magic system, though I personally can't stand it.

[Othniel Edden]

You could build into the class a personal low regen rate, and then stat individual spells to take a certain amount of hit points. I'd call this a meter system of spellcasting.

[Cerlis]

Hellfire warlock +bloodmage system. for both major and minor

P.S. The class is a 3 level class that gives +2d6 per lvl dmg dice by sacrificing 1 con point. con is your life so you are sacrificing a part of your life (its ability damage), so its a real sacrifice if you have a low con. not only does it lower your con ( a con score of 0 is death, real risky with poison). you basically choose to use hellfire when you want to and pay the penalty for the extra damage. Lowering your con also reduces your hit points (for every 2 you lose your lvl in hp) and your fort save as well as consenctration skill checks. so its a significant investment. the class is for warlocks but it even says in the column about switching it to a spellcaster class, with the main requirement of instead of it being eldritch blast it being a school of magic (suggested Evocation). So whenever i fireball or chain lighting i can choose to add 2d6 times my prestige class level to it for one concentration (if this was a main class ability you'd reduce the rate dice increase. at 9th lvl spells i think most spells do a max of 20d6 dmg so i think one bonus dice per 2 lvls makes sense as a main class)

further for lesser effects (if its a class based off bloodcasting then you'd want mulitple abilities) you might have the blood casting from the blood mage in complete arcane. one hp = 1 CL. you might, since this is a main class, have this upgrade every 4 or 5 lvls simular to how a wilder can cast at increased manifester lvl. so at 20th lvl you could save 1-5 hitpoints for 1-5 increased caster lvl.

you might have simular trade offs starting at 3rd or 5th lvl. there is a fighter feat that allows you to reduce you will save to increase your ac, and reduce your BaB to increase your will save, i think it would make sense to have an ability that for a round as an immediate action you could reduce one save to increase another by a proportional amount, or maybe half to make it more balanced. perhaps you might have this effect last an hour or even a day, to increase the idea of making a sacrifice. "if you use this ability you may leave yourself vulnerable to other dangers".

also it might be balanced to see how much HP your average healing spell can restore per spell level (a 1st lvl spell is 1d8+max10, so an average of 15 or so), and so you could sacrifice 15 HP to replenish a 1st lvl spell. a few balancing options are making it so that that ability advances slowly. kinda like a abjurant champion can instant cast Abj spells but only low lvls ones. you could do this but maybe at 20 could do max of 6th lvl spells. further, there could be a penalty. where for a number of rounds = to the spell lvl positive and negative energy both hurt you (negating healing, but only doing it for a short time, reducing the frequencing in which you do it in mid combat but giving you options during downtime) though this may still be overpowered.

[CodeRed]

Got the bug from thinking about this. Working on a 1-20 base class that shouldn't be too strong but also isn't a waste of space either. Once I got the details ironed out I'll be posting it in this thread as well as the Homebrew forum. Should be up by Monday night as I have a lot of free time right now on holiday.

[Lonely Tylenol]

My take on this would be to incorporate a hit point cost for Blood Mage spells equal to 1 point per spell level (so a 1st-level spell deals 1 point of damage, 2nd-level spell deals 2, and so on). Give it a handful of spell-like abilities that resemble life-based effects (Vampiric Touch being a cornerstone, of course) that's used a variable number of times per day (1 at 5th level, 2 at 10th level, etc; something similar to Smite Evil progression). Even Vampiric Touch and False Life would be enough; allow them to scale accordingly, but also to allow certain bonuses (such as to be treated as Empowered, as the weapon adjustment, or False Life scales down to a move, a swift, and perhaps even an immediate action).

I don't have the time to do a full write-up, but a list of effects something along these lines might be good...

BASICS:
Hit Dice: D4
Skills: 2 + INT per level
Class Skills: Concentration (CON), Craft (INT), Intimidate (CHA), Knowledge (Arcana) (INT), Knowledge (Religion) (INT), Spellcraft (INT)
Base Attack Bonus: Poor
Saves: Will good, Reflex poor, Fortitude poor
Weapon & Armor Proficiencies: None

Spells Per Day/Spells Known: A Blood Mage can cast from the Blood Mage spell list (to be written up). A Blood Mage knows every spell on their spell list, and can cast spells simultaneously, as a Sorcerer. (I'll let someone else figure this one out; I imagine it involving predominantly Conjuration, Divination, Evocation, Necromancy and Transmutation, using blood to bring things into existence, or to change things.) A Blood Mage's spellcasting is Charisma-based, and all that entails. (I really don't feel like writing this block out...)

Bloodletting: In order to cast spells, a Blood Mage must draw from their own life essences to deliver the arcane energies. When a Blood Mage casts a spell, they must take 1 point of damage per spell level of the spell being cast. For instance, to cast a 5th-level spell, a Blood Mage must take 5 points of damage during the casting, infusing their spellcasting with their own blood.
A Blood Mage can further use their bloodletting in two ways: First, a Blood Mage can use Bloodletting to pay the material components for spells with costly components. A Blood Mage may choose to take 1 hit point of damage per 25gp of the spell's material component cost. At 10th level, the Blood Mage can pay for experience costs with their own blood as well, taking 1 hit point of damage per 5xp of the spell's experience cost.
Second, at 8th level, a Blood Mage can use their life force to mitigate the spell level cost of metamagic feats. Doing so is particularly taxing, however, and thus a Blood Mage that chooses to mitigate metamagic this way takes 1 point of Constitution damage for level adjusted in this way. This damage can only be cured through 8 hours of restful sleep. A Blood Magus cannot use this ability to increase a spell's level above the highest level a Blood Mage can cast.

Stigmata: At 2nd level, a Blood Mage gains Stigmata as a bonus feat, even if they do not meet the prerequisites.

False Life: At 3rd level, a Blood Mage gains False Life 1/day as a spell-like ability with a caster level equal to the Blood Magus' class level. The Blood Mage gains an additional use of this ability every six levels beyond 3rd level. At 6th level, the Blood Mage can use False Life as a move action; at 12th level, a swift action; and at 18th level, an immediate action.

Toughness: At 4th level, a Blood Mage gains Toughness as a bonus feat.

Vampiric Touch: At 5th level, a Blood Mage gains Vampiric Touch 1/day as a spell-like ability with a caster level equal to the Blood Magus' class level. The Blood Mage gains an additional use of this ability every five levels beyond 5th.

Great Fortitude: At 7th level, the Blood Mage gains Great Fortitude as a bonus feat.

Blood Pact: At 10th level, the Blood Mage can create a bond with a single willing creature. Upon performance of the blood pact, a Blood Mage permanently loses 1 point of Constitution, and the bonded creature gains 1 point of Constitution. As long as both the Blood Magus and the creature are alive, the creature and the Blood Magus are treated as having the Share Pain ability, and when either creature takes damage, both creatures instead take half the damage. If either creature involved in the pact dies, the pact immediately ends. The Blood Mage can only maintain a blood pact with one creature at a time. The Blood Mage cannot initiate a blood pact with the same creature twice, even if one of them dies and is subsequently brought back to life. The blood pact cannot be initiated with a creature that does not have a Constitution score, or is not intelligent enough to consent to the pact.
Empower Spell-Like Ability: After much time and patience with the craft, a Blood Mage becomes more attuned to the workings of one's life forces. At 12th level, a Blood Mage gains Empower Spell-Like Ability as a bonus feat, but can only use it on Spell-Like Abilities granted by the Blood Magus class.

Blood Telepathy: As a Blood Mage advances, their knowledge of the blood pact they have undertaken becomes more refined. At 13th level, the Blood Mage shares a telepathic bond with the creature that they have initiated a blood pact with, as long as they are within one mile of each other.

Improved Toughness: A Blood Mage's constant conditioning causes them to be more resilient. At 14th level, a Blood Mage gains Improved Toughness as a bonus feat.

Blood Calling: At 16th level, a Blood Mage can call a creature with which it shares a blood pact, as long as the creature is willing to be called. This ability functions like Greater Teleportation, with the Blood Mage as the destination point. (There is probably something better to equate this to, but I'm improvising.)

Blood Mastery: At 20th level, a Blood Mage has developed their mastery of the forces of life in a number of ways, making them more resilient and fearsome. First, a 20th-level blood mage gains a permanent +4 bonus to their Constitution score, as well as a number of hit points equal to twice their HD. Further, the Blood Mage becomes immune to ability drain and energy level drain, as their blood makes them completely resilient to such effects.
Second, the Blood Mage gains fast healing 10, allowing their body to regenerate its life forces as quickly as it loses them through its arcane channeling.
Third, the Blood Mage learns how to use his very life essence as the focus of its spellcasting. A 20th-level Blood Mage can choose to use their Constitution modifier instead of their Charisma modifier to determine spells known, bonus spells, and save DC of spells. This decision is made at the time of spellcasting, and can change per each casting of a spell (for instance, if a Blood Mage has a high Constitution score at the beginning of the day, they might wish to use their Constitution score to determine all relevant modifiers; however, as they day wears on and they take Constitution damage and drain from various effects, it might be more useful to use Charisma instead).
Fourth, a Blood Mage is able to distort the pattern and flow of their blood to create a constant stench. While active, all creatures within 30 feet of the Blood Mage that have a sense of smell must make a Fortitude save (DC10+1/2 the Blood Mage's level + CON or CHA modifier) or be nauseated. A creature that succeeds in their save is instead sickened, but must make a Fortitude save each successive round they are in the aura to avoid becoming nauseated. The effect remains in place as long as the creature is within the Blood Mage's aura, and lingers for 3 rounds after. The Blood Mage can activate or de-activate this ability as a free action.

That's what I'd start with, but it's probably horribly balanced (Stigmata at 2nd level vs. Great Fortitude at 7th, for example). I also never figured out how to work scent into the package (which seems like something a Blood Mage would become more attuned to, all things considered). This is what you get for a random late posting.

[Jjeinn-tae]

My take on this would be to incorporate a hit point cost for Blood Mage spells equal to 1 point per spell level (so a 1st-level spell deals 1 point of damage, 2nd-level spell deals 2, and so on). Give it a handful of spell-like abilities that resemble life-based effects (Vampiric Touch being a cornerstone, of course) that's used a variable number of times per day (1 at 5th level, 2 at 10th level, etc; something similar to Smite Evil progression). Even Vampiric Touch and False Life would be enough; allow them to scale accordingly, but also to allow certain bonuses (such as to be treated as Empowered, as the weapon adjustment, or False Life scales down to a move, a swift, and perhaps even an immediate action).

I don't have the time to do a full write-up, but a list of effects something along these lines might be good...

BASICS:
Hit Dice: D4
Skills: 2 + INT per level
Class Skills: Concentration (CON), Craft (INT), Intimidate (CHA), Knowledge (Arcana) (INT), Knowledge (Religion) (INT), Spellcraft (INT)
Base Attack Bonus: Poor
Saves: Will good, Reflex poor, Fortitude poor
Weapon & Armor Proficiencies: None

Spells Per Day/Spells Known: A Blood Mage can cast from the Blood Mage spell list (to be written up). A Blood Mage knows every spell on their spell list, and can cast spells simultaneously, as a Sorcerer. (I'll let someone else figure this one out; I imagine it involving predominantly Conjuration, Divination, Evocation, Necromancy and Transmutation, using blood to bring things into existence, or to change things.) A Blood Mage's spellcasting is Charisma-based, and all that entails. (I really don't feel like writing this block out...)

Bloodletting: In order to cast spells, a Blood Mage must draw from their own life essences to deliver the arcane energies. When a Blood Mage casts a spell, they must take 1 point of damage per spell level of the spell being cast. For instance, to cast a 5th-level spell, a Blood Mage must take 5 points of damage during the casting, infusing their spellcasting with their own blood.
A Blood Mage can further use their bloodletting in two ways: First, a Blood Mage can use Bloodletting to pay the material components for spells with costly components. A Blood Mage may choose to take 1 hit point of damage per 25gp of the spell's material component cost. At 10th level, the Blood Mage can pay for experience costs with their own blood as well, taking 1 hit point of damage per 5xp of the spell's experience cost.
Second, at 8th level, a Blood Mage can use their life force to mitigate the spell level cost of metamagic feats. Doing so is particularly taxing, however, and thus a Blood Mage that chooses to mitigate metamagic this way takes 1 point of Constitution damage for level adjusted in this way. This damage can only be cured through 8 hours of restful sleep. A Blood Magus cannot use this ability to increase a spell's level above the highest level a Blood Mage can cast.

Stigmata: At 2nd level, a Blood Mage gains Stigmata as a bonus feat, even if they do not meet the prerequisites.

False Life: At 3rd level, a Blood Mage gains False Life 1/day as a spell-like ability with a caster level equal to the Blood Magus' class level. The Blood Mage gains an additional use of this ability every six levels beyond 3rd level. At 6th level, the Blood Mage can use False Life as a move action; at 12th level, a swift action; and at 18th level, an immediate action.

Toughness: At 4th level, a Blood Mage gains Toughness as a bonus feat.

Vampiric Touch: At 5th level, a Blood Mage gains Vampiric Touch 1/day as a spell-like ability with a caster level equal to the Blood Magus' class level. The Blood Mage gains an additional use of this ability every five levels beyond 5th.

Great Fortitude: At 7th level, the Blood Mage gains Great Fortitude as a bonus feat.

Blood Pact: At 10th level, the Blood Mage can create a bond with a single willing creature. Upon performance of the blood pact, a Blood Mage permanently loses 1 point of Constitution, and the bonded creature gains 1 point of Constitution. As long as both the Blood Magus and the creature are alive, the creature and the Blood Magus are treated as having the Share Pain ability, and when either creature takes damage, both creatures instead take half the damage. If either creature involved in the pact dies, the pact immediately ends. The Blood Mage can only maintain a blood pact with one creature at a time. The Blood Mage cannot initiate a blood pact with the same creature twice, even if one of them dies and is subsequently brought back to life. The blood pact cannot be initiated with a creature that does not have a Constitution score, or is not intelligent enough to consent to the pact.
Empower Spell-Like Ability: After much time and patience with the craft, a Blood Mage becomes more attuned to the workings of one's life forces. At 12th level, a Blood Mage gains Empower Spell-Like Ability as a bonus feat, but can only use it on Spell-Like Abilities granted by the Blood Magus class.

Blood Telepathy: As a Blood Mage advances, their knowledge of the blood pact they have undertaken becomes more refined. At 13th level, the Blood Mage shares a telepathic bond with the creature that they have initiated a blood pact with, as long as they are within one mile of each other.

Improved Toughness: A Blood Mage's constant conditioning causes them to be more resilient. At 14th level, a Blood Mage gains Improved Toughness as a bonus feat.

Blood Calling: At 16th level, a Blood Mage can call a creature with which it shares a blood pact, as long as the creature is willing to be called. This ability functions like Greater Teleportation, with the Blood Mage as the destination point. (There is probably something better to equate this to, but I'm improvising.)

Blood Mastery: At 20th level, a Blood Mage has developed their mastery of the forces of life in a number of ways, making them more resilient and fearsome. First, a 20th-level blood mage gains a permanent +4 bonus to their Constitution score, as well as a number of hit points equal to twice their HD. Further, the Blood Mage becomes immune to ability drain and energy level drain, as their blood makes them completely resilient to such effects.
Second, the Blood Mage gains fast healing 10, allowing their body to regenerate its life forces as quickly as it loses them through its arcane channeling.
Third, the Blood Mage learns how to use his very life essence as the focus of its spellcasting. A 20th-level Blood Mage can choose to use their Constitution modifier instead of their Charisma modifier to determine spells known, bonus spells, and save DC of spells. This decision is made at the time of spellcasting, and can change per each casting of a spell (for instance, if a Blood Mage has a high Constitution score at the beginning of the day, they might wish to use their Constitution score to determine all relevant modifiers; however, as they day wears on and they take Constitution damage and drain from various effects, it might be more useful to use Charisma instead).
Fourth, a Blood Mage is able to distort the pattern and flow of their blood to create a constant stench. While active, all creatures within 30 feet of the Blood Mage that have a sense of smell must make a Fortitude save (DC10+1/2 the Blood Mage's level + CON or CHA modifier) or be nauseated. A creature that succeeds in their save is instead sickened, but must make a Fortitude save each successive round they are in the aura to avoid becoming nauseated. The effect remains in place as long as the creature is within the Blood Mage's aura, and lingers for 3 rounds after. The Blood Mage can activate or de-activate this ability as a free action.

That's what I'd start with, but it's probably horribly balanced (Stigmata at 2nd level vs. Great Fortitude at 7th, for example). I also never figured out how to work scent into the package (which seems like something a Blood Mage would become more attuned to, all things considered). This is what you get for a random late posting.

Ooh, I like this... Might have to give it a spell list sometime for my own use.

[gomanfox]

I saw a system that kinda fits this in a Slayers d20 book once, although the system may be in use in other places as well. If I remember correctly, instead of being limited by spells-per-day, spellcasters take non-lethal damage whenever they cast a spell. They would also make Fortitude saves each time they cast a spell (DC based on the spell level?) and if they make them, they reduce the amount of damage they take. If they fail, they take double the normal amount of damage and have to make some other roll to see if they lose control of the spell. Failing the check by 10 or more makes the caster fatigued (or exhausted if already fatigued). Plus, if the caster is exhausted when they cast a spell, the nonlethal damage becomes lethal damage.

The Slayers d20 system allows non-spellcasting classes to learn magic as well, but the actual spellcasting classes get far more spells, and get bonuses to their Fortitude saves to resist the spell drain, so if you used a similar system, you'd want to include something like that since spellcasters don't always have good Fortitude saves.

I think from what I've heard, the actual Slayers d20 magic system isn't balanced very well, with the DCs of high level spells being too difficult for even high level casters to be able to cast successfully, but other than that I thought it was a pretty nifty system.