Death Throes. When Xzen'toth dies, it explodes, and each creature within 30 feet of it must make a DC 20 Dexterity saving throw, taking 70 (20d6) fire damage on a failed save, or half as much damage on a successful one. The explosion ignites flammable objects in that area that aren't being worn or carried, and it destroys Xzen'toth's weapons.

Fire Aura. At the start of each of Xzen'toth's turns, each creature within 5 feet of it takes 10 (3d6) fire damage, and flammable objects in the aura that aren't being worn or carried ignite. A creature that touches Xzen'toth or hits it with a melee attack while within 5 feet of it takes 10 (3d6) fire damage.

Magic Resistance. Xzen'toth has advantage on saving throws against spells and other magical effects.

Magic Weapons. Xzen'toth's weapon attacks are magical.

Multiattack. Xzen'toth makes two attacks with its greatsword.

Greatsword. Melee Weapon Attack: +14 to hit, reach 10 ft., one target. Hit: 21 (5d12 + 8) slashing damage plus 13 (3d8) fire damage. If Xzen'toth scores a critical hit, it rolls damage dice three times, instead of twice.

(1 action) Attack  Xzen'toth makes one melee weapon attack at a target within range.

(2 actions) Stomp  Xzen'toth stomps on the ground, causing all targets within a 30' radius to make a DC 22 Strength save or be knocked back 20' and prone, and take 16 (3d10) bludgeoning damage.

(3 actions) Life Drain Melee Weapon Attack: +14 to hit, reach 5 ft., one creature. Hit: 76 (16d8 + 4) necrotic damage. The target must succeed on a DC 22 Constitution saving throw or its hit point maximum is reduced by an amount equal to the damage taken, and the damage heals Xzen'toth by that amount. This reduction lasts until the target finishes a long rest. The target dies if this effect reduces its hit point maximum to 0.