Mobile. Reindeer can take the disengage action as a bonus action

Gore. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 8 (2d4 + 3) piercing or slashing damage.

Storm Retaliation. Once per turn, when a creature within 5 feet of you that you can see hits you with an attack, you can use your reaction to cause the creature to make a Dexterity saving throw. The creature takes 1d8 lightning or thunder damage (your choice) on a failed saving throw, and half as much damage on a successful one.