Multiattack

The guardian attacks twice with its slam.

Slam

Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 13 (2d8 + 4) bludgeoning damage.

Hurl Object

Ranged Weapon Attack: +7 to hit, range 20/60 ft., one target. Hit: 18 (4d6 + 4) bludgeoning damage.

Lightning Bolt (1/Day, While Bloodied)

An 80-foot-long 5-foot-wide lightning bolt springs from the guardians chest. Each creature in the area makes a DC 15 Dexterity saving throw taking 28 (8d6) lightning damage on a failed save or half damage on a success.