Excavating Anurid

When this creature enters, you may sacrifice a land. If you do, draw a card.
Threshold — As long as there are seven or more cards in your graveyard, this creature gets +1/+1 and has vigilance.

Crucible of Worlds

The Gitrog Monster

Deathtouch
At the beginning of your upkeep, sacrifice The Gitrog Monster unless you sacrifice a land.
You may play an additional land on each of your turns.
Whenever one or more land cards are put into your graveyard from anywhere, draw a card.