Inscrutable.

The sphinx is immune to any effect that would sense its emotions or read its thoughts, as well as any divination spell that it refuses. Wisdom (Insight) checks made to ascertain the sphinx's intentions or sincerity have disadvantage.

Magic Weapons.

The sphinx's weapon attacks are magical.

Spellcasting.

The sphinx is a 12th-level spellcaster. Its spellcasting ability is Wisdom (spell save DC 18, +10 to hit with spell attacks). It requires no material components to cast its spells. The sphinx has the following cleric spells prepared:

Cantrips (at will): sacred flame, spare the dying, thaumaturgy
1st level (4 slots): command, detect evil and good, detect magic
2nd level (3 slots): lesser restoration, zone of truth
3rd level (3 slots): dispel magic, tongues
4th level (3 slots): banishment, freedom of movement
5th level (2 slots): flame strike, greater restoration
6th level (1 slot): heroes' feast

Actions

Multiattack.

The sphinx makes two claw attacks.

Claw.

Melee Weapon Attack: +12 to hit, reach 5 ft., one target. Hit: 17 (2d10 + 6) slashing damage.

Roar (3/Day).

The sphinx emits a magical roar. Each time it roars before finishing a long rest, the roar is louder and the effect is different, as detailed below. Each creature within 500 feet of the sphinx and able to hear the roar must make a saving throw.

First Roar. Each creature that fails a DC 18 Wisdom saving throw is frightened for 1 minute. A frightened creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.
Second Roar. Each creature that fails a DC 18 Wisdom saving throw is deafened and frightened for 1 minute. A frightened creature is paralyzed and can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.
Third Roar. Each creature makes a DC 18 Constitution saving throw. On a failed save, a creature takes 44 (8d10) thunder damage and is knocked prone. On a successful save, the creature takes half as much damage and isn't knocked prone.

Legendary Actions

The androsphinx can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature's turn. The androsphinx 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.

Lair Actions

On initiative count 20 (losing initiative ties), the sphinx can take a lair action to cause one of the following magical effects; the sphinx can't use an effect again until it finishes a short or long rest:

The flow of time is altered such that every creature in the lair must reroll initiative. The sphinx can choose not to reroll.
The effects of time are altered such that every creature in the lair must succeed on a DC 15 Constitution saving throw or become 1d20 years older or younger (the sphinx's choice), but never any younger than 1 year old. A greater restoration spell can restore a creature's age to normal.
The flow of time within the lair is altered such that everything within moves up to 10 years forward or backward (sphinx's choice). Only the sphinx is immediately aware of the time change. A wish spell can return the caster and up to seven other creatures designated by the caster to their normal time.
The sphinx shifts itself and up to seven other creatures it can see within in its lair to another plane of existence. Once outside its lair, the sphinx can't use lair actions, but it can return to its lair as a bonus action on its turn, taking up to seven creatures with it.

Environment: Desert

Androsphinx