Trepidation Sprawl

At the beginning of each upkeep, that player
chooses a land. That land's controller sacrifices it.
Exile two land cards from a graveyard: Create a
black Nightmare creature token with "This
creature's power and toughness are each equal
to the number of land cards in all graveyards."
Activate this ability only any time you could
cast a sorcery and only once each turn.