Mournwillow is a uncommon Creature — Plant Skeleton card from Eldritch Moon (EMN), collector number 187. Current market price: $0.08 (foil $0.45), TCGplayer market prices via Scryfall.
Haste Delirium — When this creature enters, if there are four or more card types among cards in your graveyard, creatures with power 2 or less can't block this turn.