Auranthra, the Riddleweaver

Spellcasting. Auranthra, the Riddleweaver is a 9th-level spellcaster. Its spellcasting ability is Intelligence (spell save DC 16, +8 to hit with spell attacks). Auranthra, the Riddleweaver has following wizard spells prepared:
Cantrips (at will): Mage Hand, Prestidigitation, Minor Illusion, Message 

1st level (4 slots):  Detect Magic, Shield, Mage Armor, Magic Missile

2nd-level (3 slots): Mirror Image, Suggestion, Detect Thoughts

3rd-level (3 slots): Counterspell, Lightning Bolt, Major Image

4th-level (3 slots): Dimension Door, Stoneskin

5th-level (2 slots): Teleportation Circle, Scrying

Multiattack: Auranthra makes two claw attacks or casts a spell and makes one claw attack.

Claw: Melee Weapon Attack: +8 to hit, reach 5 ft., 1 target. Hit: 18 (3d8 + 4) slashing damage. 

Stoneskin: When attacked, Auranthra, the Riddleweaver casts Stoneskin on itself.

• Teleport (Costs 2 Actions): Auranthra magically teleports, along with any equipment she is wearing or carrying, up to 60 feet to an unoccupied space she can see.
• Spell (Costs 2 Actions): Auranthra casts a spell from her list of prepared spells.
• Etherealness (Costs 3 Actions): Auranthra magically enters the Ethereal Plane from the Material Plane, or vice versa. She is visible on the Material Plane while in the Border Ethereal, and vice versa, yet she can't affect or be affected by anything on the other plane.
• Legendary Actions (3/Day): Auranthra 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. Auranthra regains spent legendary actions at the start of her turn.