View Full Version : Help designing a monster

2009-07-23, 07:29 PM
Here's the skinny:

In my Iron Heroes game, the PCs will be making their way to a village that is currently worshipping one of the many "gods" in the world. This "god" is little more than a glorified hydra.


It is more like a classical Greek hydra - one of the heads is immortal, so it can't be killed (although it can be defeated), and its bite is poisonous. I'm figuring 7-headed hydra, increase the CR to reflect the poisonous bite.

More over, it is intelligent and can talk - in fact, it has a little deal with the cult who worships it and has control over this village. Also, the PCs can talk to it and possibly get relevant information out of it.

The hydra isn't the challenge. In fact, the hydra has been bound by "godsteel" (effectively, adamantium) to its cave by one of the heroes of yore some time ago. The challenge will be two - the cultists, armed with poisoned weapons and wearing shed hydra scales as armor... and the "baby" hydras.

See, the monsters in this world (or at least, this particular monster) tend to be asexually in their reproduction, but only if they have been getting enough to eat.

Given that the party will consider of 4 PCs and 2 NPCs, all level 2, what are people's thoughts for how to design the babies, including the Challenge Rating for them?

2009-07-23, 07:37 PM
It depends on how many there are; a good idea might be to have four or five CR2 babies.
Give them a weak poison, low Fort save (12-14) for 1d4 points of str, con, or dex damage.
They should probably have only two or three heads, and have low attack bonuses-+3 or so sounds right. The actual bite damage should be minimal (1d3+1, maybe), as the main challenge is the poison. Leave the actual hp damage up to the villagers.
That being said, there's no reason to make these guys an easy win. Give each hydra around fifteen hitpoints, and an AC of 17-19 to assure that a single magic missile or hit won't finish them off, and even primary combatants will miss less than they'll hit.
On reflection, these seem a little weak. Tweak the DC for the poison up to 16 (or 15 if you feel generous), and if you want this to be tough make the ability damage 1d3+1 instead of 1d4...or if you feel cruel, make it 1d4+1. This should assure that, while not being overwhelming, the players will once or twice get a nasty shock from the poison.

2009-07-23, 08:31 PM
Perhaps you should consider giving them regeneration, in the troll sense.

But instead of having four or more from the get go, have the big Hydra spawn a new one every second round or so, to a certain maximum (5 or so).

All in all, it would make a little more interesting, and memorable encounter, just make sure to give the players some clues as to what sort of damage or action they need to use or perform to permanently kill the buggers.

2009-07-23, 08:36 PM
Its a house rule but in my games i make natural armor like normal armor giving damage reduction instead of ac i feel it makes more sense.

These baby hydras do you picture a massive swarm of size small or even tiny vicious poisonous ankle bitters. Or a couple powerful size medium or even large monsters?

2009-07-23, 09:40 PM
Now that I have a little more time, let me work through a bit, get some reaction.

Given that a horse (Large) gives birth to a foal (Small) and a human (Medium) gives birth to a baby (Tiny), I think having a Huge Magical Beast have Medium-sized babies.

So reducing the Hydra to Medium gives -16 Str, +4 Dex, -8 Con, -5 natural armor, +2 AC/Attack due to size.

Physical stats for a baby are now: Str 3, Dex 16, Con 15, AC 16 (+3 Dex, +3 natural armor).

Dropping to 3-heads makes the baby Hydra from 7d10+38 (77 hp) to 3d10+6 (22 hp). It also loses 4 from its BAB from its size and 8 from its diminished Strength. This means that has an attack of -1 total. Its bite goes from 1d10+4 to 1d6-4. This is good, because Iron Hero uses damage reduction for armor (like awa posted), where Leather Armor (which most of the group wears) provides 1d2 DR. So it is possible for the baby Hydra to actually hit AND do damage.

And once the baby hydra does damage, the poison takes effect. I think this should be like Wyvern Poison (2d6 initial, 2d6 secondary), only this is reduced two steps to 2d3? 1d6? 1d8? No, 1d6, initial and secondary. The DC is 10 + 1/2 the heads + Con modifier, so DC 14 (adult DC 20).

Fasting healing drops from 17 to 13 (with 22 hp, that's going to be an interesting and long body if they don't do it right), Fort +5, Ref +4, Will +1 (most likely, haven't figured the mental stats yet).

It has Combat Reflexes, Iron Will (so make the Will +3 at least), and Toughness (so hp 25).

If a pyro- or cryo-hydra with 7 heads is CR 8, the baby should be CR 2 (3 heads + 1 for poison - 2 for being Small). A good fight for 6 level 2 PCs... 3 babies? 2 babies with 2 CR 1 cultists? 1 babies with 4 CR 1/2 cultists?

How does that look?

Also, a "child" hydra... Str 11, Dex 14, Con 19... 5 heads... AC 16 (-1 size, +2 Dex, +5 natural)... HD 5d10+20 (50 hp)... bite +4, 1d8, poison of 1d8 Con initial, 1d8 Con secondary, DC 17, CR 5

2009-07-23, 10:34 PM
I would point out that most reptiles are vastly smaller when their babies then mammals.

While your math looks good it in my mind doesn't feel right size medium creatures with 3 strength don't seem particularly fearsome

I feel you would be better off making it from the ground up rather then doing it that way.

I think the whole forcing sunder works much less well when they are fighting multiple creatures at once i would probably lose the fast heal all together

also an armiger could easily make a build immune from the babies attack using that design.

2009-07-23, 10:51 PM
Babies, as in, just born, probably are a little unsteady on their feet. As in, NOT fearsome, exactly...

So, yes, making the baby hydra with a Strength 3 DOES feel right. If I want to give them a little progress, I'll bump up the Strength a point or two to show that it's been around for a while.

Given that I am dealing with 4 PCs, 2 NPCs, all level 2, I don't think that them ganging up on one or two will be a problem. I think the issue is - how much support do the baby hydras get? I'm thinking that the cultists will be trying to smuggle them out of the village, so maybe only one baby, one cultist leader (CR 1), 2 mook cultists (CR 1/2) - against 6 2nd-level Iron Heroes? Maybe a little tough, but not a problem for the party. I'm thinking I should probably make it two babies and 4 mooks.

As for an armiger, sure. No problem. But the thing is, I know they won't have an armiger with them. In fact, the biggest threat would be if the player of the arcanist makes it, especially since he's got a berserker NPC tag-along. (And realistically, the idea of using armor to deal with a couple of monster babies makes a LOT of sense - it's like handling rattlers - it helps to wear good cowboy boots.)

The others? Thief - leather. Man-at-arms - I THINK leather. Archer - leather. Executioner - leather. Harrier - leather. Weapons master - leather. They are great at moving silently, but not so much on taking massive amounts of damage.

Kol Korran
2009-07-24, 11:53 AM
i don't know iron heroes, but i have a few things to suggest:
1) be aware that with 1d6-4, they probably won't be able to damage anyone with any armor better than leather. (i guess better armors get better DR than 1d2?). also, even with the enemies that do wear leather armor, the hydra has a chance of (1/6*1/2)= 1/12 to actually cause damage. most chances the party will get read of it way sooner than that, and that the babies will be a joke. the first one will be more confusing just due to their fast healing, but the party could probably easely take it down with focused attacks to the body, or by the usuall method of lopping of heads. part of the reason hydras are a terror is because when you try to chop a head, the rest attack you. but with them barely able to hit, that would be negligable.

i suggest one of two things- either have the hydra babies with increas bite out put (i suggest simply 1d3 or 1d4. not strictly by the rules, but who cares. say that they are born especially savage to survive the harsh world), or instead... have the hydra head with the poisoned bite, able to spit the poison. that way it can also hit ranged characters (if they are close enough)... say, a posion spit weapon it can spit once every 1d4 rounds, (or perhaps even change it to a very short cone?)

2) the poison: you're intending to use a lot of posion, and that could eaely overwhelm the group, especially since it's CON posion who also reduces their hit points, and makes it harder to resist further poisons... (again, there might be some migitating rules for that in iron kingdoms, i'm talking from the regular D&D POV). i suggest you make the cultists poisons fairly weak (1d2 con primary and secondery, perhaps with some minor effect as being dazed, easy DC such as 11-13) and the baby hydras posion a bit tougher (1d4 con, DC 14)
this will still make the challange hard, but managable. i suggest you enable the party to get by 2-3 vials of antipoison before the challange (perhaps meeting the village hunter who deliver meat to the babies?)

3) check my sig, and scroll down until you see pics of a hydra. i've added and changed some material on the hydra that you might find in use, especially for the intelligent hydra. i'll be glad if anyone uses it. let me know if it worked for you!


2009-07-24, 02:11 PM
Kol Karran - Kinda.

Improved armor increases the DR dice. Studded leather gives DR 1d3, chain shirt is 1d4, scale is 1d5, chain mail 1d6, and so on.

However, the Armor Mastery feat increases the DR, so it would not be difficult to have the DR jump up to 1d2 + 2 or more quite easily.

Iron Heroes involves Defense (to hit the target) and Damage Reduction (to actually damage the target).

So I did a few numbers, and this is what I get:

At Strength 3, the baby hydra has a -4 to hit and -4 damage. With 3 heads, that's 3 chances and +3 BAB, so -1 to hit, -4 damage total.

Assuming the average PC in my group has a Defense of 14 (+3 Dex, +1 BDB (Base Defense Bonus)) and leather armor, I'm looking at the following chances to just HIT on a single all-out attack.

14 - (-1) = 15 to better to hit. 30% chance.
70% * 70% * 70% = 34.3% of all 3 heads missing... so 65.7% chance that at least ONE head will hit.

As you pointed out, there is only a 1 in 12 chance of the hydra actually damaging the PC, so that's 8.33% of 65.7%, or 5.48% total.

Say the baby hits and actually hurts someone. The poison DC is 14. The average PC has a Fort Save of +4 (Con 14, 2nd level Iron Heroes PC), so they will make it 55% of the time for the initial. So 45% to fail, or 2.46% to take 1d6 Con damage (and depending on the Con damage, the secondary might be more likely to fail, so let's skip that one).

That's per round. Assume that baby lives 4 rounds (one for no one attacking it, one for the confusion as it isn't hit hard enough, and then two more for the PCs pounding the geezus out it), that's 97.54% ^ 4 = 90.5% chance of the hydra doing nothing before dying, or a 9.5% chance of being effective.


Bumping the Strength up to 5 (give the baby a few months to grow), we have...

+0 hit, -3 damage.
35% chance to hit.
27.5% chance to miss with all 3 heads. 72.5% chance to hit with at least one.
From 1 in 12 to 3 in 12 to actually get through the armor. 72.5% * 25% = 18.1% chance of actually damaging the PCs on any given round.
45% chance of failure, so 8.2% chance of poisoning one of the PCs.
91.8% chance of being ineffective for one round, 71.1% chance of being ineffective before dying.
So... 28.9% chance of actually being effective.


That's not bad. Make it two baby hydras, drop the poison to 1d4.


Kol Korran
2009-07-24, 02:59 PM
i can think of only one main poit i want to add-
first decide on the effect, or the efficiency you want your critters to have, and THEN work out the numbers to accomodate them, not the other way around... you're the DM- you can give whatever justification you want, as long as it serves the story well enough. besides- your players realy aren't going to complain (or even notice) whether the monsters had stregth 5 or 7 for that matter.

how often do you think the players should be hit? how much damage should they incur? (i get it that you want the posion to be the main thing, damaging only serving to get the posion to affect)? how hard should be the poison to resist, and what should be the consequences?

first determine how many baby hydra encounter you may want. from the top of my head i can think of 3:
- meeting a baby one that may have gone a bit away from the main cluster- a sort of introductory encounter.
- a meeting with a baby hydra and cultists, working together. the encounter has 3 goals: showing that the cultis rever the hydra, showing the the baby hydra have some intelligence and can work together, and giving a battle with different opponenet types.
- once they are more into the hydra caves, the party meet a small bunch of smaller, baby hydra, who's threat is in their numbers. this also shows that if not dealt with, in several years or decades, these monsters could spread far and wide. the battle is made more difficult if you use the poison spitting hydra version rather than the biting one, since the smaller kinds are even less effective.

once you've determined the number of hydras, and of cultists, you have a basic frame work to prepare to your adventure. again- first decide what you need, then how you get it.
(possible explenations:
- "hydras are vicious creatures, greatly feared and hunted extensively since birth. due to natural selection they have grown tougher offsprings then comparative ones of other species"
- "the proginator hydra have been instructing her cultists how to groom and breed her children into greater power, greater savagry. there could have been many more baby hydras, but the proginator wished only for excellent specimen to grow and survive, she expects her brood to excel.")

hope this helped. i guess my link hasn't realy.

2009-07-24, 04:22 PM
I would tend to stay away from CON poison for parties of low level since they are usually ill equipped to handle poison and any low CON/HP character becomes that much more vulnerable. I would suggest STR poison.

Also the baby hydra's are OK but they lack oomph. I do think a CR 4 normal 5 headed hydra may be a little too much for the party (though this depends a lot on the party, situation and tactics). However you could tone down the CR 4 hydra a little to make an "adolescent" version for a solo boss monster. You could use the same stats as a CR4 hydra except 4 HD, 45 hp, 4 attacks at +5 for 1d8+3 + DC 12 poison 1d4 STR/1d4 STR. You could also remove the head regenaration if the party has few reliable means of causing acid or fire damage (again that depends on party composition, preparation or tactics). Also keep in mind that a hydra is not that dangerous an opponent for the party if they can keep it a distance or run away from it.

And in case you need some variety, I would also say that in addition to "baby hydras" and cultists you could also use any "scaly" level monster such as medium pythons or vipers, a monitor lizard, a shocker lizard, or a felldrake, as setting appropriate monsters.

2009-07-24, 05:37 PM
In the Iron Kingdoms campaign setting they have a hydra that has only a single head when it's born and aquires the others by killing it's nest mates and grafting them onto itself via fast healing. Your "baby hydras" could just be large vipers with fast healing.

2009-07-24, 06:33 PM

Okay, I'm going to spoiler this just in case any of my players actually wanders in and reads this.

(I.e., if you are one of my players, get the **** out of this thread!!!)

How do I want this encounter(s) to pan out?

Short answer: I don't know.

Long answer: My gaming group tends to be long on role-playing, short on combat. As such, I tend to weaken the monsters I throw at them because it doesn't seem like they are able to fight on-par with most other groups.

Then they turn around and wiped the floor with my CR 3 Demonic Brute without taking more than a few scratches. When they were 1st level. As in, not a challenge.

So I figure it's time to up the ante a little, give them something more like a challenge.

The background to this setup is that the PCs are tracking down a book that was stolen, and they know that the thief was in this village a few days ago, but they know nothing of this village (research, Knowledge (local) rolls might change that).

The story is that a particular hydra is chained with a long chain in a cave just outside the village proper. The hydra itself is NOT suppose to be a combat encounter. It has made the best of its cruel and sadistic existence as it can, and wants to use the villagers and its young as best it can to create as much chaos and destruction as it can (partly out of spite).

The hydra, the cult leader, and one other villager knows where the thief went after visiting the village, so ultimately the PCs will show up, get the information, and move on.

This is, of course, glossing over a few details, like how the villagers and the monsters are going to react and how the PCs get the information in the first place.

The first "encounter" is going to be an ambush (lookouts, nowhere to hide while on the path, the village has elevation, etc.) by a bunch of villagers who are trying to take one of the PCs prisoner (to be sacrificed to their "god"). They don't really want to hurt anyone, but they figure, better them than us (lots of opportunity for RP here, as the PCs are being attacked by "sad" men who keep saying, "I'm sorry, I have no choice, our god wills it, etc."). They will be using nets and clubs, but the moment one of them gets hurt, the "better them than us" becomes "better you than me". The villagers will abandon the nets and turn on their fallen friend, apologizing, but taking him away to be a sacrifice (while he screams all the time - more RP).

(I figure about 30 villagers should be enough to both ensnare the PCs and form a blockade to prevent them from mettling while they drag off their fallen comrade.)

The trouble is, that's about as far as I have firmly established (as far as plot). I don't want to make a railroad plot, so I mostly want a few "events" to happen. For example, the hydra has a few babies, which only the cult leader and the leader's bodyguards know about.

I figure I'll use the Demonic Minion template for the cult leader (as the hydra benefits turn the human into a kind of monster as well - I'm thinking 2 claw attacks at 1d4 base damage and a minor poison (DC 12)). The bodyguards are just Level 1 Warriors (albeit armed with poisoned weapons, probably DC 11).

I know that I want there to be combat between this group and the PCs, but not with the villagers at large (who are mostly innocent) or the hydra itself (because it would be too difficult a fight for the PCs) - in part, I want this because one of the players was a little antsy about the LACK of combat, so I figured I would mix things up for him (the other players are okay with combat, not wanting to do only RPing all game session long).

Now adding things like vipers and whatnot could be interesting. Also, making the baby hydra essentially a multi-headed viper is a nice idea... but then, the idea of describing the baby hydra as a "mini-saurpod" and being "almost cute" is too much of a temptation to pass.

Any thoughts?

2009-07-24, 06:52 PM
Response spoilered

CR is a very rough guide. A CR 3 encounter might be hard for one group but easy for another.

One thing to determine is not how how you want the encounters to go but what encounters you want.

So you've already said that you want

- the first encounter to be an ambush by villagers, a plot hook if you will

If that first encounter fails to get the PCs to visit your dungeon then set up a follow on plot hook, eg the thief they are chasing was ambushed and sent on to the dungeon.

Now you also want
- an encounter with 1 or more baby hydras
- an encounter with the warped leader of the cult and his bodyguards
- (assuming) last encounter to be a non-combat encounter with an immortal hydra

So far so good. I continue to recommend that
- you use STR not CON poison and not use poison for all the encounters, especially the earlier ones. For ex if the baby hydras are poisonous and the cult leader is poisonous, make an earlier encounter in the dungeon a python instead of a viper.
- sprinkle a couple of more encounters in the dungeon like snakes lizards or such
- make the "baby hydras" a little more powerful however cute they are. One way to do that is to trim down a CR 4 hydra in HD and damage and perhaps head regeneration especillay if you add poison. Another is to essentially treat it as a multi-headed viper.

2009-07-24, 08:41 PM
one thing you could do to reduce the effects of the poison is have some antidote to said poison somewhere the pcs can eventually find it. If the poison is really stomping the players cause it to heal damage already taken if the poison is proving not particularly dangerous give it some minor effect like a bonus on the saves

2009-07-24, 10:12 PM
...I like that one, awa. Thanks!

Just something else...

Had a talk with someone, bounced a few ideas off. Had a great one. Have the cult have a faction that is trying to take over. A evil with many heads...