Righteous Sentinel

The sentinel is immune to any spell or effect that would alter its form.

The sentinel has advantage on saving throws against spells and other magical effects.

The sentinel’s weapon attacks are magical.

The sentinel has disadvantage on attack rolls against creatures that haven’t hit it within the last minute. In addition, it has advantage on attack rolls against a creature if the creature dealt damage to it in the previous round.

Any time the sentinel is targeted by a ranged spell attack roll, roll a d6. On a 5, the sentinel is unaffected. On a 6, the sentinel is unaffected and the spell is reflected back at the caster as though it originated from the sentinel, turning the caster into the target.

The righteous sentinel makes two slam attacks.

Melee Weapon Attack: +9 to hit, reach 5 ft, one target. Hit: 16 (2d10 + 5) bludgeoning damage.

The righteous sentinel points its shield at a creature within 30 feet of it. If the target can see the sentinel's shield, the target must make a DC 15 Wisdom saving throw. On a failure, the target takes 22 (4d10) psychic damage and is frightened for 1 minute. On a success, the target takes half the damage and isn't frightened. An evil-aligned target has disadvantage on this saving throw. At the start of each of the frightened creature's turns, it takes 11 (2d10) psychic damage. It can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

The sentinel adds 3 to its AC against one melee attack that would hit it. To do so, the sentinel must see the attacker. If the attack misses, the attacker takes 11 (2d10) psychic damage.