Sub-Zero of the Lin Kuei

Prowess (Whenever you cast a noncreature spell,
this creature gets +1/+1 until end of turn.)
Whenever you cast or copy an instant or sorcery
spell, you may tap target creature and put a stun counter on it. (If a permanent with a stun counter
would become untapped, remove one from it instead.)
Fatality — {1}{u}{u}: Destroy target creature with
three or more stun counters on it.