Charge. If the sheep moves at least 20 feet straight toward a target and then hits it with a ram attack on the same turn, the target takes an extra 5 (2d4) bludgeoning damage. If the target is a creature, it must succeed on a DC 13 Strength saving throw or be knocked prone.

Sure-Footed. The sheep has advantage on Strength and Dexterity saving throws made against effects that would knock it prone.

Ram. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 8 (2d4 + 3) bludgeoning damage. 
 
Poisonous Bite. Melee Weapon Attack: +5 to hit, reach 5ft., one creature. Hit: 6 (1d6 + 4) piercing damage. The target must make a DC 15 Constitution saving throw, taking 12 (3d6) poison damage on a failed save, or half as much damage on a successful one.