Acid Absorption. Whenever the tophet is subjected to acid damage, it takes no damage and instead regains a number of hit points equal to the acid damage dealt.

Acidic Aura. The area around the tophet is think with acidic green mist stinging the eyes and sinuses of all creatures within 30 feet of the tophet. All attack rolls and ability checks made in the aura that rely on hearing, sight, or smell are made at disadvantage.

Creatures immune to acid damage are unaffected by the Acidic Aura.

Immutable Form. The tophet is immune to any spell or effect that would alter its form.

Magic Resistance. The tophet has advantage on saving throws against spells and other magical effects.

Magic Weapons. The tophet's weapon attacks are magical.

Multiattack. The tophet makes two claw attacks.

Claw. Melee Weapon Attack. +10 to hit, reach 10 ft., one target. Hit: 20 (4d6 + 6) slashing damage plus 9 (2d8) acid damage.

Spew Acid (Recharge 5-6). The tophet opens the hatch on its abdomen releasing the acid stored inside. The acid shoots in a line 60 feet long and 5 feet wide. All creature in the area of effect must succeed on a DC 17 Dexterity saving throw or take 54 (12d8) acid damage, half damage on a successful saving throw.