Baba Yaga

Fear, Haste
Whenever Baba Yaga attacks or you cast a sorcery
or intant black spell put a House Counter on
Baba Yaga.
Then if have 6 counters on it, create Monster
House, a legendary 5/7 black construct artifact
creature with Hexproof, Indestructible, Vililance
and "Baba Yaga can't leave the battlefield until
Monster House leave the battlefield".