Kulrath Knight 
Creature — Elemental Knight
Flying Wither (This deals damage to creatures in the form of -1/-1 counters.) Creatures your opponents control with counters on them can't attack or block.
Legality
standardNOT LEGALpioneerNOT LEGALmodernLEGALlegacyLEGALvintageLEGALcommanderLEGAL