Ob Nixilis, the Fallen is a mythic Legendary Creature — Demon card from Tarkir: Dragonstorm Commander (TDC), collector number 192. Current market price: $2.72, 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.