Multiattack.

The mirager makes two slam attacks.

Slam

Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 6 (1d6 + 3) bludgeoning damage.

Thirst Kiss

The mirager feeds on the body moisture of creatures it lures into kissing it. A creature must be charmed, grappled, or incapacitated to be kissed. A kiss hits automatically, does 21 (6d6) necrotic damage, and fills the mirager with an exultant rush of euphoria that has the same effect as a heroism spell lasting 1 minute. The creature that was kissed doesn't notice that it took damage from the kiss unless it makes a successful DC 16 Wisdom (Perception) check.

Captivating Dance (Recharges after a Short or Long Rest, Humanoid Form Only)

The mirager performs a sinuously swaying dance. Humanoids within 20 feet that view this dance must make a successful DC 16 Wisdom saving throw or be stunned for 1d4 rounds and charmed by the mirager for 1 minute. Humanoids of all races and genders have disadvantage on this saving throw. A creature that saves successfully is immune to this mirager's dance for the next 24 hours.