It seems to me that 4e monster Hit Points don’t scale properly.
From examining the MM3 on a business card, we see that every level, monsters get +1 to hit, defenses, and damage. At level 1, they have about 32 HP, and they get 8 HP per level.
(From what I’ve seen, PCs tend to have comparable to-hit, defenses, and at-will damage. Of course, over the course of a fight, PCs are better than monsters, due to encounter and daily powers, feats, and other complications. In the simplest cases, though, PCs and monsters can stand in for each other.)
So what’s the problem? As far as I can see, the monster math above suggests that at higher levels, fights will drag on longer as monsters gain proportionally more HP. And indeed, in practice, I see this happening. I recently ran a level 30 adventure, and the fights took forever. Here’s why:
Take a level 1 monster. He has 32 HP. He (and his opponents) do an average of 9 points of damage per hit. That’s great! That means it will take about 4 hits to kill a monster. A highly damaging hit (a crit or encounter power) might bloody the monster in one hit. That feels exactly right to me. In fact, according to this excerpt from Player’s Strategy Guide, 4 hits per monster is the design intention: “Assume that your heroes can kill a typical monster with four successful attacks.”
At level 1, we are exactly on target. However, monsters gain 8 HP per level! That means, in order to keep up, the PCs (who should be able to kill a monster in 4 hits) need to increase their average damage by 2, every level. In order to stay on par, all level-30 PCs (leaders and controllers as well as strikers) would need to be doing about 70 damage per hit. There’s no way they can do that! The result? Monster HP outstrips PC damage.
At level 10, a monster will have 96 HP. With PC damage averaging around 18 HP per hit, it will now take 6 hits to kill the monster.
At level 30, a monster has 264 HP. PCs at that level should do an average of 38 damage per at-will hit. That means it takes an epic PC 7 hits to kill a monster of equal level – almost twice as long as it took at level 1. And while it was possible to bloody a level 1 monster with one lucky hit, it is very unlikely that even a level 30 PC will be able to do 132 HP of damage in one hit. An optimized uberPC might be able to do it, but certainly not Joe Sixmead.
By the way, monsters’ 8 HP per level is way more than PCs get. Weak PCs (wizards and such) get 4 per level. Strong PCs (fighters, for instance) get 6.
The fix? The average monster gains 4 HP per level (brutes 6). To accomplish this, subtract 4 HP per level from every monster. This will balance nicely with the recent much-needed damage boost provided by Monster Manual 3. Now, at every level, it will always take the average PC 4 hits to kill the average monster.
As a sanity check, let’s do the math with a level 30 creature. He’d have 144 HP. The PCs, doing damage of 38 per hit, would kill him after 4 hits. And the monster’s Bloodied value, 72, is quite achievable with a single PC crit or encounter/daily power.
Putting it all together:
On-the-fly fix for Monster Manual 1 Monsters
- Add +1/2 damage per level to every attack (the Monster Manual 3 fix)
- Subtract 4 HP per level (the Paul fix)
Note: Based on good points raised in the comments, I’m amending my recommendation: instead of subtracting HP per level, subtract 3 HP per level. The extra 1 HP/level is absorbed by high-level characters’ increased damage on critical hits and encounter powers. If I err in any direction, though, I’d like to err towards shorter combats, since each high-level turn takes so much longer.