Because I've d12 hit dice fuckers!

Hit Points

The formula for calculating the hit points is:

HP = Total Value of Constitution + Average Hit Dice or Hit Dice rolled

To calculate hit points use the following table.

ClassHit Points on First LevelHit Points per level gained
ArtificerCON Value + 1d8 (5)+ 1d8 (5)
BarbarianCON Value + 1d12 (7)+ 1d12 (7)
BardCON Value + 1d8 (5)+ 1d8 (5)
ClericCON Value + 1d8 (5)+ 1d8 (5)
DruidCON Value + 1d8 (5)+ 1d8 (5)
FighterCON Value + 1d10 (6)+ 1d10 (6)
MonkCON Value + 1d8 (5)+ 1d8 (5)
MysticCON Value + 1d8 (5)+ 1d8 (5)
PaladinCON Value + 1d10 (6)+ 1d10 (6)
RangerCON Value + 1d10 (6)+ 1d10 (6)
RogueCON Value + 1d8 (5)+ 1d8 (5)
SorcererCON Value + 1d6 (4)+ 1d6 (4)
WarlockCON Value + 1d8 (5)+ 1d8 (5)
WizardCON Value + 1d6 (5)+ 1d6 (5)

Why this change?

This change has three main purposes:

Let’s take a look at the following graph:

It’s on the early levels and we can already see that a fighter will only have fewer hitpoints on the first level.

In this case is clear that Constitution can’t be 10 for a Fighter, and the Hit Dice means almost nothing for the Fighter, it’s only the stat that really matters.

With this approach on the first level the wizard will have more HP (due to the high constitution), but the disparity is reduced. An after that all the levels the fighter will have higher HP.