Mirage Body. The wurm constantly emits a shimmering heatwave that makes its form difficult to perceive. Attacks against it are made with disadvantage unless the attacker has truesight. When the wurm is reduced below half its hit points, it can use its reaction to disappear and reappear 60 feet away, leaving an illusory double in its original location.

Desert Ambush. If the wurm attacks a creature within 60 feet of an illusory double it created, the target has disadvantage on saving throws against the wurm's abilities.

Mirage Plane. Once per day, the wurm can pull all creatures within 60 feet into a shimmering mirror-like mirage. In this plane, all terrain appears flat and endless, and the horizon shimmers with the illusion of water. Each creature must make a DC 18 Constitution saving throw at the end of each of its turns or gain a level of exhaustion. Creatures in this plane cannot benefit from effects that reduce exhaustion. The Mirage Plane lasts until the wurm chooses to end it as a bonus action, or after 1 minute.

Multiattack. The Desert Mirage Wyrm makes three attacks: one with its Bite and two with its Tail.

Bite. Melee Weapon Attack: +12 to hit, reach 10 ft., one target. Hit: 19 (3d8 + 6) piercing damage plus 13 (3d8) psychic damage.

Tail. Melee Weapon Attack: +12 to hit, reach 15 ft., one target. Hit: 16 (3d6 + 6) bludgeoning damage, and the target must succeed on a DC 18 Strength saving throw or be knocked prone.

Thirst of the Wurm(Recharge 5-6). The wurm releases a wave of dehydrating heat in a 60-foot cone. Each creature in the area must make a DC 18 Constitution saving throw. On a failed save, a creature takes 35 (10d6) fire damage and gains a level of exhaustion. On a success, it takes half damage and doesn’t gain exhaustion.

The sphinx 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 sphinx regains spent legendary actions at the start of its turn.

Claw Attack. The sphinx makes one claw attack.

Teleport (Costs 2 Actions). The sphinx magically teleports, along with any equipment it is wearing or carrying, up to 120 feet to an unoccupied space it can see.

Cast a Spell (Costs 3 Actions). The sphinx casts a spell from its list of prepared spells, using a spell slot as normal.