Bulwark Ox (DFT 532)

Creature — Ox Mount • Mana cost: {1}{W} • Aetherdrift • Rare

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.)

Illustrated by Jon Vermilyea.