Hold Breath. The elemental can hold its breath for 30 days.

False Appearance. While motionless, the elemental looks like a large fallen log.

Surprise Attack. If the elemental surprises a creature and hits it with an attack during the first round of combat, the target takes an extra 7 (2d6) damage from the attack.

Born of Oblivion. The elemental is unaffected by the slowing and restraining effects of the Swamp of Oblivion’s mud.

Legendary Resistance (2/Day). If the elemental fails a saving throw, it can choose to succeed instead.

Multiattack. The elemental makes four attacks: one with its bite, two with claws, and one with its tail. The attacks with the bite and tail cannot be made against the same targets.

Bite. Melee Weapon Attack: +14 to hit, reach 5 ft., one target. Hit: 29 (4d10 + 7) piercing damage, and the target is grappled (escape DC 21). Until this grapple ends, the target is restrained, and the crocodile can't bite another target.

Claw. Melee Weapon Attack: +14 to hit, reach 5 ft., one target not grappled by the elemental. Hit: 17 (3d6 + 7) slashing damage.

Tail. Melee Weapon Attack: +14 to hit, reach 15 ft., one target not grappled by the elemental. Hit: 20 (3d8 + 7) bludgeoning damage. If the target is a creature, it must succeed on a DC 21 Strength saving throw or be knocked prone.

Breath of Oblivion ([rollable](Recharge 5–6);{"diceNotation":"1d6","rollType":"recharge","rollAction":"Breath of Oblivion"}[/rollable]. The elemental exhales toxic sulfurous fumes that rot and consume flesh. Each creature inside a 60-foot cone originating from the elemental must make a DC 19 Constitution saving throw or take 49 (9d10) necrotic damage and become poisoned. A creature that succeeds on its save takes half damage and isn’t poisoned. A creature that is grappled by the elemental has disadvantage on this save.

The elemental can take 2 legendary actions, 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 elemental regains spent legendary actions at the start of its turn.

Snap. The elemental makes one Bite attack.

Dive (Costs 2 Actions). The elemental dives beneath the mud, which triggers no opportunity attacks, and moves up to its swimming speed to a different unoccupied space on the surface. It can be partially submerged. Each creature within 5 feet of where the elemental surfaced must make a DC 19 Dexterity saving throw or be immediately subjected to the slowing effects of the Swamp of Oblivion’s mud.