Burning Touch. Any melee attack made against the Acid Golem takes 3D6 acid damage. 

Holding Form. This feature is treated like a concentration spell. You must make a concentration roll each time you are struck by an attack. Failing the roll causes you to drop the form. 

Healing Touch. After the Acid Golem form is dropped Yazid is restored to full Hp. 

Multiattack. The Acid Golem can make 3 attacks with its Acid Punch or with its Acid Ball

Acid Punch. Melee Weapon Attack: +11 to hit, reach 10 ft., one target. Hit: 30 (3d10 + 10) acid damage.

Acid Ball. Ranged Weapon Attack: +11 to hit, reach 30 ft., one target. Hit: 25 (2d10 + 5) acid damage.

Acid Hug. Any enemy creature makes a DC 20 dexterity saving throw. On a failed save a creature that is smaller than this one with 75 hp or less remaining is instantly melted. A larger creature than the Acid Golem or a creature that has more than 75 hp left takes 10D8 Acid Damage. On a successful save the creature takes  half as much.