Sadrik said:
Also, how does a level 6 skirmisher monster get 47/23 HP (from the spine devil stat card)
I have no idea how they got the HP's on that creature.
My best guess from everything I've heard is that creatures hitpoints, BAB, and saves aren't based on a formula so much as a "balanced against the players" ideal.
They said they hated the fact that you'd make a 20 hitdice creature and it would give you so much bab, so much saves, so much hitpoints, etc.
So, I think the hitpoints got to be there like this:
The average PC does...let's say 12 damage per hit at about 6th level. We think a battle is no fun unless the enemy survives about 5 rounds. That gives us around 60 hitpoints. Since encounters should have about 1 enemy per PC, each one will have to do about enough damage to kill any one of them in the 5 rounds. This is a skirmisher so it is supposed to be weaker than average for his level. Let's take off around one round worth of hitpoints from him, making...around...47.
The reason I believe this is because of comments made by the devs saying things like "DR is bad because it adds another factor when estimating how many rounds it takes for a PC to defeat an enemy. Normally you just need hitpoints, ac, and attack bonus." Also, the above complaints that hitdice were tied to bab, skills and saves. They wanted a method to make one creature have large amounts of hitpoints and still have no skillpoints and only have a BAB of 1.
So, the only way to do this is to stop tying any of these things to level. You can instead have guidelines per level, but no rules. They've said it's easier to develop monsters and this would help. They also said they wanted to fix the fact that they continually got stat blocks wrong and one of them made a comment that they didn't think there should be such thing as "wrong". They've said they didn't like formulas that created unfun creatures. Plus they've also made comments that they had a formula that worked on all monsters in terms of hitpoints, attack bonuses, and defenses. That they changed the formula once and they knew exactly how to change every monster in the monster manual based on that change.
Thus, the easiest formula(and the one that causes the most fun battles) is one that takes into account the damage of the party, the hitpoints and ac of the enemy and an estimated time the battle should take before it ends.