Bulwark Ox is a rare Creature — Ox Mount card from Aetherdrift (DFT), collector number 532. Current market price: — (foil $2.72), TCGplayer market prices via Scryfall.
Whenever this creature attacks while saddled, put a +1/+1 counter on target creature. Sacrifice this creature: Creatures you control with counters on them gain hexproof and indestructible until end of turn. Saddle 1 (Tap any number of other creatures you control with total power 1 or more: This Mount becomes saddled until end of turn. Saddle only as a sorcery.)