Ruin Crab is a uncommon Creature — Crab card from Zendikar Rising (ZNR), collector number 75. Current market price: $1.67 (foil $2.30), TCGplayer market prices via Scryfall.
Landfall — Whenever a land you control enters, each opponent mills three cards. (To mill a card, a player puts the top card of their library into their graveyard.)