Warhorse Zombie, Variant (5e Creature)
From D&D Wiki
Large beast, neutral evil
Undead Fortitude. If damage reduces the zombie warhorse to 0 hit points, it must make a Constitution saving throw with a DC of 5 + the damage taken, unless the damage is radiant or from a critical hit. On a success, the zombie warhorse drops to 1 hit point instead.
Hooves. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 11 (1dX + 2d6 + 4) damtype damage.