ok so since you don't feel like reading ill post here for you. if you keep saying that I am saying it grants temporary hp, I will have no need to respond to you anymore.
Frenzy: (1 AP, Barbarian Level 6). Activation Cost: 10 Hit Points. Cooldown: 30 seconds. Enter a frenzy, increasing your strength by +2 and adding Vicious to your melee weapons. You gain +30 hit points and +10 healing amplification.
it COSTS 10 hp to activate.
you GAIN 30 hp
30 - 10 = +20 hp. its LIKE temporary hp and just LIKE temporary hp it will go away eventually.