Ancient Guardian

Destructible Legs. For every 20 hit points of damage, the Ancient Guardian takes, it loses one of its 6 legs and 10 feet of movement.

Vulnerable Eyes. If the Ancient Guardian is hit with a critical hit from a ranged weapon attack, it becomes stunned until the end of its next turn, ignoring the immunity to the condition.

Multiattack. The Ancient Guardian takes 2 claw attacks, so long as it has 1 leg remaining.

Claw. Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit: 8 (1d8 + 4) [Slashing] damage. 

Minor Blast. Pick a point within 120 feet of the Ancient Guardian. All creatures within 10 feet of that point must make a DC 15 Dexterity saving throw or take 15 (4d6+2) radiant damage on a failed save and half as much on a success.

Eye Blast (Recharge 5-6). Pick a point within 120 feet of the Ancient Guardian. All creatures within 20 feet of that point must make a DC 15 Dexterity saving throw or take 30 (8d6+2) radiant damage and get launched 10 ft away from the blast on a failed save and half as much on a success.