Chameleon Grimjaw

Legendary Resistance (3/Day). If the Chameleon Grimjaw fails a saving throw, it can choose to succeed instead.

Naturally Lucky. The Grimjaw scores a critical hit on an attack roll of 18-20.

Radiation. For purposes of damage resistances and immunities, the Chameleon Grimjaw's melee attacks are considered magical.

Frightening Strength. If a creature is frightened of the Chameleon Grimjaw, and the Chameleon Grimjaw makes an attack against the creature, its attack damage is doubled. Additionally, on a successful attack, the Chameleon Grimjaw is healed for an amount of health equal to half the amount of damage it dealt.

Invisible Skin. As an action, the Chameleon Grimjaw gains the effects of an "Invisible" spell, which lasts one minute. After using this ability, the Chameleon Grimjaw is unable to do so for one minute

Multiattack. The Chameleon Grimjaw can make either two Slash attack actions, or one Charge attack action and one Slash attack action.

Slash. Melee Weapon Attack: +11 to hit, reach 10 ft., one target. Hit: 21 (2d10 + 8) Slashing damage. 

Charge. Melee Weapon Attack: +11 to hit, reach 5 ft., one target. Hit: 29 (6d6 + 8) Slashing damage. Must have moved 10 feet in the direction of the target before use.

Rock Throw. Ranged Weapon Attack: +13 to hit, range 25/40 ft. one target. Hit: 30 (4d10 + 8) Bludgeoning damage.

Emboldening Roar. As an action, the Grimjaw lets out a massive roar, causing any creature within 90 feet of it to make a DC 15 Wisdom saving throw. On a fail, the creature becomes frightened until the beginning of the Grimjaw's next turn.

The Chameleon Grimjaw can take 3 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 Chameleon Grimjaw regains spent legendary actions at the start of its turn.

Frightful Stare. The Chameleon Grimjaw fixes its gaze on a creature it can see within 60 feet of it. The creature must succeed on a DC 18 Charisma saving throw, or become frightened by the Chameleon Grimjaw until the beginning of the Grimjaw's next turn.

Radiant Infusion. The Chameleon Grimjaw infuses it's attacks with radioactive power. On its next turn, every attack made deals an additional die in Radiant damage.

Terrifying Invisibility (costs 3 actions). If the Chameleon Grimjaw is invisible via it's "Invisible Skin" ability, it can use this legendary action and, at the beginning of it's next turn, it's able to make an attack against a creature without losing its "invisible" condition. If the Chameleon Grimjaw uses this legendary action during the last round, it is unable to do so again until the next round. While the Chameleon Grimjaw is invisible, it is unable to use the "Multiattack" action.