Agwynn, the Great Fey Spirit of Spring

Bound by the Crown. Agwynn is permanently bound to the Crown of the Fey, one of the four Artifacts of the Fey. The wielder of the Crown is the only person that Agwynn serves, and she chooses when to fight and when to not fight. As a free action at the start of her Wielders turn, she can choose to Merge with them if they are willing. If she does that, she disappears, reforming after the two split once more. 

Origin Caster. Agwynn can concentrate on up to 3 spells at once. When she fails a saving throw to maintain concentration, she chooses which spell ends first. 

Legendary Resistance (1/day). When Agwynn fails a saving throw, she can choose to succeed instead. 

Multiattack. Agwynn makes 2 Sigil Beam attacks. She can replace any number of them with a use of Spellcasting. She can then use Spellcasting. 

Sigil Beam. Dexterity Saving Throw: DC 20, each creature in a 120 foot line. Failure: 22 (4d10) Force damage. Success: Half damage. Failure or Success: Each creature Agwynn’s choice that moves through the Line’s speed increases by 10 feet until the end of their turn. 

Spellcasting. Agwynn casts one of the following spells, using Charisma as her spellcasting ability (Save DC 20): 
At Will: Charm Person, Guiding Bolt (Force Damage), Animal Friendship, Animal Messenger, Beast Sense, Calm Emotions, Chromatic Orb (3rd level), Command
2/day total: Mass Suggestion, Guiding Bolt (5th level, Force Damage), Bow of the Great Spirit.

Mirror Magic (recharge 5-6). As a reaction to taking damage from a spell, Agwynn conjures a magical mirror, negating the spell’s effects and reflecting them back at the caster. Use the Caster’s own Spell Save DC and Spell Attack Bonus when a spell is reflected against them. 

Reflexive Teleport. As a reaction to taking damage, Agwynn teleports to any unoccupied point within 10 feet of her Wielder.