Darth Nihilus

Wither

{1}{w}{b}{r}: Target creature gains Lifelink until end of turn. Activate this ability only as a sorcery and only once each turn.

Whenever you gain life, put X +1/+1 counters onto Darth Nihilus, Essence Eater equal to half the amount of life you gained rounded down.

Whenever a noncombat source you control deals damage, you gain that much life.