Altered HP Rules for Difficulty (Need Opinions)

[Captain Zark]

So I'm going to be running a new campaign in a few days and I wanted some opinions on the rule on HP I plan on using.

For the sake of adding difficulty, I was going to have HP calculated as Constitution Score + Con. Mod. So, at most, a player could have 20 HP at level 1 (Using Point Buy or Standard Stats with a +2 to Con.).

For levelling, I was going to have it raised based on class (+3 for Barbarians, +2 for Fighters, Paladins, and maybe Clerics, and +1 for Druids, Monks, Rangers and Rogues. Bards, Sorcerers, Warlocks, and Wizards will remain constant.

Hit Dice will be rewarded with Ability score increases (1d12 for Barbarians, 1d10 for Fighters/Pallies/Clerics, 1d8 for Druids/Monks/Rangers/Rogues, and 1d6 for the rest)

I will most likely make similar adjustments to enemies and NPCs.

What do you guys think? What should I alter?

[TheTeaMustFlow]

Basically everything combat-related in the game is balanced upon HP increasing in the manner in which they do. Without rewriting virtually every such thing in the game, by which point it will be essentially a completely different game, past about level 3 or so this is a fantasically bad idea.

[p_johnston]

I think that this might be a bit to much of a cut to HP.

https://1drv.ms/w/s!Ah1xkdAG-Z8vgUTDxBbb-XrcHzz5

I created a quick table comparing the average DPS of monsters by CR to the HP of characters by level in your system. About level four is where a monster of CR equal to the party can now one shot the barbarian.

The problem with putting HP so low is that the damage of everything in the monster manual will scale faster then player HP. So you end up with one of two scenarios at higher level.
1)The party won initiative- The monster/monsters are dead. They didn't get to act.
2)The Enemies won Initiative- The party is dead. They didn't get to act.

It might not be quite as bad as that but it will be close.

P.S. I actually experimented with a system to cut down HP myself.
https://1drv.ms/w/s!Ah1xkdAG-Z8vgUKMFX38wmh9AxCF
It's the first section of the above document if you want to pillage it for ideas. I can tell you that It has been working fine for my group so far (although they are only level four so....). Two things though.
1)I'm only willing to mess with the HP system like this because I"m keeping the campaign low level. I put a hard cap of level 11 on the group and leveling is slow. They will likely never reach the cap.
2)I still have to adjust every monster the party faces from the MM. I found that with that system wants Monster HP about .6 of whatever the MM says.

[Final Hyena]

For the sake of adding difficulty, I was going to have HP calculated as Constitution Score + Con. Mod. So, at most, a player could have 20 HP at level 1 (Using Point Buy or Standard Stats with a +2 to Con.).

Interestingly this makes most people have higher than normal HP at 1st level.

For levelling, I was going to have it raised based on class (+3 for Barbarians, +2 for Fighters, Paladins, and maybe Clerics, and +1 for Druids, Monks, Rangers and Rogues. Bards, Sorcerers, Warlocks, and Wizards will remain constant.

having Bards, Sorcerers, Warlocks and Wizards stay the same is potentially very punishing if you go past the early levels.
Also there is a mix up of some classes. It seems that
d12 -> 3
d10 -> 2
d8 -> 1
d6 -> 0
but cleric a d8 is at 2, ranger a d10 is at 1, bard a d8 is at 0, warlock a d8 is at 0.
I think something along the lines of;
4; Barbarian
3; Fighter, Paladin, Ranger
2; Cleric, Monk, Bard, Druid, Rogue, Warlock
1; Wizard, Sorcerer

There is also the hp increasing racial trait of hill dwarves the toughness feat and class bonuses (sorcerer). I would alter the racial trait and feat, but leave the dragon sorcerer alone.

Hit Dice will be rewarded with Ability score increases (1d12 for Barbarians, 1d10 for Fighters/Pallies/Clerics, 1d8 for Druids/Monks/Rangers/Rogues, and 1d6 for the rest)

Spending a hit dice gives you a bonus to an ability score?

I think the general idea is alright but after a few levels you will find the game balance to get trickier to keep a grasp on as HP is less than intended but damage output continues as normal. This also makes blasting characters more powerful.

[Captain Zark]

The idea was to make my players think before they act instead of blindly killing anything they see. The campaign I'm running is most likely just going to be a 5hr one-off, so I'm not exactly expecting the players to go above level 4.

Having Bards, Sorcerers, Warlocks and Wizards stay the same is potentially very punishing if you go past the early levels.
Also there is a mix up of some classes. It seems that
d12 -> 3
d10 -> 2
d8 -> 1
d6 -> 0
but cleric a d8 is at 2, ranger a d10 is at 1, bard a d8 is at 0, warlock a d8 is at 0.
I think something along the lines of;
4; Barbarian
3; Fighter, Paladin, Ranger
2; Cleric, Monk, Bard, Druid, Rogue, Warlock
1; Wizard, Sorcerer

Thanks, I wasn't quite sure where I should put things. I've only run a few short campaigns, and I've only seen wizards, out of all the "pure" (I guess you could say) spellcasters, at play.

There is also the hp increasing racial trait of hill dwarves the toughness feat and class bonuses (sorcerer). I would alter the racial trait and feat, but leave the dragon sorcerer alone.

I'll probably leave them all alone for the sake of allowing more health for the characters (The campaign is going to be entirely dwarven PCs.) Additionally, I was going to allow them, as a "downtime activity", to train and they could get that +1/+2/+3 additional health per level.

Spending a hit dice gives you a bonus to an ability score?

No no no. When a player would normally get an ability score increase (Level 4, 8, 12, 16, 19) they'd also get an additional hit dice. It'd look like 1dX at level 1, 2dX at level 4, 3dX at level 8 and so on.

[Demonic Spoon]

The idea was to make my players think before they act instead of blindly killing anything they see. The campaign I'm running is most likely just going to be a 5hr one-off, so I'm not exactly expecting the players to go above level 4.

There are tons of ways you could raise the lethality of combat without implementing houserules that require you rebalance the whole game.
For one, you could just make combats harder, and maybe add in some more punishing rules for going to 0 HP.