Adjust Mana

The caster adjusts their self to the oncoming wave of attacks, making them immune to one certain type of attack(piercing, lightning, cold, poison, etc.) to such an extent that any attack of that type will heal them rather then harm them. If the caster is already at maximum hit points, then the energy absorbed is stored for later. Each 10 hp translates to an extra 1d10 die that the caster uses on their next attack. If the caster is hurt while they have stored energy, the energy automatically reverts to HP until full.