Blood of an Immortal

Choose a creature within range including yourself, for the duration you gain a number of dice equal to 1 plus the spell level used to cast this spell. The die type is the same as the target's Hit Die (for instance if the target is a Barbarian the die would be D12 and if the target were a Wizard the die would be 1D6)

Once per round, for the duration, when the target of this spell takes damage, roll one of these die and regain hit points equal to the number rolled.