Necrotic Wound 
Instant
Undergrowth — Target creature gets -X/-X until end of turn, where X is the number of creature cards in your graveyard. If that creature would die this turn, exile it instead.
Legality
standardNOT LEGALpioneerLEGALmodernLEGALlegacyLEGALvintageLEGALcommanderLEGAL