Awakened Shield Guardian

Regeneration only. The shield guardian regains 10 hit points at the start of its turn if it has at least 1 hit point. Other than that the shield guardian cannot benefit from any form of healing.

Stored Magic. Its former master stored aura of vitality stone shape inside the guardian, which it can cast once per day requiring no components.

Heart of Metal. This guardians masters amulet is incorporated in its form protected by some metal plating and see through cristal. The heart has AC 25 and 25 hit points. When the heart is destroyed, so is the shield guardian.

Multiattack. The guardian makes two fist attacks.

Fist. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 14 (2d8 + 5) bludgeoning damage.

Energy Burst (Recharge 5-6). The guardian releases a burst of stored energy in a 15-foot radius. Each creature in that area must make a DC 16 Dexterity saving throw, taking 21 (6d6) force damage on a failed save, or half as much damage on a successful one.

! Requires casting first !

Aura of Vitality. Healing energy radiates from you in an aura with a 30-foot radius. Until the spell ends, the aura moves with you, centered on you. You can use a bonus action to cause one creature in the aura (excluding you) to regain 2d6 hit points.

Constructed  to Shield. When a creature makes an attack against another creature within 5 ft. of the awakened shield guardian, the guardian can grant a +2 bonus to the attacked creature's AC.