Onmath, Locus of the Void

Landfall — Whenever a land enters the
battlefield under your control, exile up to
3 cards from all graveyards. If 2 or more
creature cards were exiled this way, create
a 2/3 green black nightmare elemental
creature token. If 2 or more instants or
sorceries were exiled this way, you may
have target player discard a card.
You may play land cards exiled with Omnath.