Animated Armor Sentinel

Antimagic Susceptibility. The armor is incapacitated while in the area of an antimagic field. If targeted by dispel magic, the armor must succeed on a Constitution saving throw against the caster's spell save DC or fall unconscious for 1 minute.

False Appearance. While the armor remains motionless, it is indistinguishable from a normal suit of armor.

Reactive. The sentinel can take one reaction on every turn in combat.

Sentinel. Whenever you hit a creature with an opportunity attack, its speed drops to 0 for the rest of the turn. This stops any movement they may have been taking. Creatures within your reach provoke opportunity attacks even if they took the Disengage action.

Spear. Melee Weapon Attack: +3 to hit, reach 10 ft., one target. Hit: 5 (1d8 + 1) piercing damage.

Sentinel. When a creature within reach makes an attack against a target other than the sentinel (and the target doesn't have the sentinel feat), the sentinel can use it's reaction to make a melee weapon attack against the attacking creature.