Corroding Touch. The Corroded Gargoyle’s melee weapon attacks deal an additional 2d6 acid damage if the target fails a DC  14 Constitution saving throw.

Rusting Presence. The Corroded Gargoyle exudes an aura of decay within a 10-foot radius. At the start of each creature's turn within the aura, they must succeed on a DC 15 Constitution saving throw or take 7 (2d6) acid damage. Objects made of metal within the aura visibly corrode, taking a permanent and cumulative -1 penalty to AC if they are armor or to damage rolls if they are weapons.

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

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

False Appearance. While the gargoyle remains motionless, it is indistinguishable from an inanimate, corroded statue.

Multiattack. The Corroded Gargoyle makes two melee attacks or one stone dive.

Bite. Melee Weapon Attack: +8 to hit, reach 5 ft., one target.
Hit: 15 (2d10 + 4) piercing damage plus 7 (2d6) acid damage.

Hook. Melee Weapon Attack: +8 to hit, reach 5 ft., one target.
Hit: 12 (2d6 + 5) slashing damage plus 7 (2d6) acid damage and if the target is a creature, it is grappled (escape DC 17).

Stone Dive. If a creature is grappled by a Gargoyle, it can fly up into the air and must move at least 20 feet straight towards the ground, pile driving the grappled creature. The creature must succeed on a DC 18 Strength saving throw, on a failure they take 28 (8d6) bludgeoning damage, and are left prone.

The Corroded Gargoyle can take 2 legendary action, choosing from the options below. Only one legendary action option can be used at a time, and only at the end of another creature's turn. The Corroded Gargoyle regains spent legendary actions at the start of its turn.

Corroding Leap. The Corroded Gargoyle leaps up to 20 feet to an unoccupied space it can see, forcing all creatures within 5 feet of its landing point to make a DC 15 Dexterity saving throw. On a failed save, the creature takes 10 (3d6) acid damage and is knocked prone.

Leaping Hook. The Corroded Gargoyle lurches towards a creature within 20 feet and makes a hook attack.