Crystal Sage

Legendary Resistance (1/Day, or 2/Day in Lair). If the Crystal Sage fails a saving throw, it can choose to succeed instead.

Fey Ancestry. The Crystal Sage has advantage on saving throws against being charmed, and magic can't put them to sleep.

Crystal Casting. The Crystal Sage can cast or use the Crystal Shard attack through any Sage Crystal within 50 ft. as if they were in that square, this effect continues through one crystal to the next. (For example the crystal Sage can't cast through a sage crystal 150 ft. away but if there were 2 crystals in-between placed at 50 ft. and 100 ft. then the Sage could cast through the crystal 150 ft. away) 

Multiattack. The mage makes two Crystal Shard attacks.

Crystal Shard. Melee or Ranged Attack Roll: +5, reach 5 ft. or range 120 ft. Hit: 7 (2d4 + 2) Magical Piercing damage.

Crystal Explosion. The Sage chooses a Sage Crystal within 120 ft. That crystal explodes forcing all creatures within 10 ft. to make a dexterity saving throw (DC 14) taking 3d4 + 2 Magical Piercing damage on a failed throw or half as much on a successful one.

Spellcasting. The mage casts one of the following spells, using Charisma as the spellcasting ability (spell save DC 14):

At Will: Detect Magic, Light, Mage Armor (included in AC), Mold Earth, Clairvoyance (This spell only applies to a Sage Crystal)
2/Day Each: Erupting Earth, Wall of Stone (This spells appearance takes that of crystal plates)
1/Day Each: Dust Devil  (level 3 version), [Tooltip Not Found] (This spell summons 3d4 + 2 Sage Crystals in occupied locations within 180 ft. of the caster)

Crystal Step (3/Day). The mage casts Misty Step, using the same spellcasting ability as Spellcasting with the condition that the range is unlimited as long as the caster remains on the same plane of existence and teleports to a space previously occupied by a Sage Crystal. The crystal targeted by this spell is shattered.

Protective Magic of the Sage (2/Day). The mage casts Counterspell or Shield in response to the spell’s trigger, using the same spellcasting ability as Spellcasting.

Legendary Action Uses: 2 (3 in Lair). Immediately after another creature’s turn, the Sage can expend a use to take one of the following actions. The Sage regains all expended uses at the start of each of its turns.

Command of the Sage. The Sage uses Spellcasting to cast Command (level 2 version) targeting a creature wielding a Sage Crystal.

Crystal Ambush. The Sage casts Crystal Step and then makes a Crystal Shard Attack

Summon Crystal (2 Actions). The Crystal Sage summons 1d4 + 1 Sage Crystals in unoccupied locations within 180 ft.

Sageful Rejuvenation (3 Actions). The Crystal Sage heals hit points equal to 10 + the number of Sage Crystals they have deployed. This actions shatters a Sage Crystal of the Sage's choice.