Unohana Retsu, the Death Sword

Indestructible, haste
{2}{p/b}: Put a siphon counter on target creature
or player. (At the beginning of each upkeep each
player and creatures with a siphon counter take 1
damage, and you gain 1 life for each counter .)
{3}{p/w}: Destroy target creature with a siphon
counter.
{4}{p/r}: After target creature attacks, untap it and
all creatures it's owner controls. After this phase,
there is an additional combat phase.