Isaac, Forgemaster

{1}{w}{b}, Pay 4 life: Return target creature
card with mana value X or less from your graveyard to the battlefield, where X is the amount of life you gained this turn, put a finality counter on that creature, then if you control five or more creatures with finality counters on them, remove all finality counters from creatures you control.

{1}{u}{b}, Pay 4 life: Regenerate target creature you control.