Valakut Exploration

Landfall - Whenever a land enters the battlefield
under your control, exile the top card of your
library. You may play that card for as long as it
remains exiled.
At the beginning of your end step, if there are
cards exiled with Valakut Exploration, put them
into their owner's graveyard, then
Valakut Exploration deals that much damage to
each opponent.