Ob Nixilis, the Fallen is a mythic Legendary Creature — Demon card from The List (PLST), collector number IMA-101. Current market price: $5.77, TCGplayer market prices via Scryfall.
Landfall — Whenever a land you control enters, you may have target player lose 3 life. If you do, put three +1/+1 counters on Ob Nixilis.