Adaptive Defense. Whenever the guardian takes damage, it gains Resistance to that damage type until the end of its next turn. If it already had Resistance to that damage type, it instead gains Immunity to that damage type until the end of its next turn. If it already had Immunity to that damage type, it instead regains 10 Hit Points. 

Multiattack. The guardian makes two attacks.

Crushing Fist. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 13 (2d8 + 4) Bludgeoning damage. If the target is a Large or smaller creature, it must succeed on a DC 15 Strength saving throw or have the Prone condition. 

Adaptive Energy Bolt. Ranged Spell Attack: +7 to hit, range 30 ft., one target. Hit: 10 (3d6) Force damage or damage of the same type as the most recent damage it took since its last turn. 

Arcane Pulse (Recharge 5 - 6). Strength Saving Throw: DC 15, each creature in a 20-foot Emanation originating from the guardian. Failure: 21 (6d6) Force damage and the target is pushed up to 10 feet away from the guardian in a straight line. Success: Half damage only.

Mirror Strike. Trigger: The guardian is hit with a melee attack roll made within 5 feet of the guardian. Response: The attacker is targeted with the same attack roll with a +3 bonus to the attack roll. If the attack hits the attacker, the attacker suffers the attack's damage with a +3 bonus to the damage roll.