Crowned Madness, Prince Cauchemar

Prince’s Madness- Whenever this monster casts a damage dealing spell, he heals himself twenty-five percent of the damage dealt.

Spellcasting. Crowned Madness, Prince Cauchemar is a 4th-level spellcaster. Its spellcasting ability is Charisma (spell save DC 15 , +5 to hit with spell attacks). He has following spells prepared:
Cantrips (at will): Chill Touch, Thaumaturgy

1st level (5 slots): Command, Magic Missile, Inflict Wounds

2nd level (4 slots): Crown of Madness, Transfer Life, Misty Step

Strike: +6 to hit, reach 10 ft., one target. Hit: (3d10 + 4) force damage. 

Physic Claw: +5 to hit, range 5/100 ft., one target. Hit: (5d8 + 4) necrotic damage.

Shatter Mirror: +4 to hit, area of effect 5 by 5 ft. Hit: (2d10 +3) force damage. This mirror can no longer be traveled through.

This monster has 1 legendary action. 

Mirror Path (Costs 1 Actions). Creates two mirrors on the map, one directly in front of this monster and another up to 60 ft. away. This monster can travel through one mirror and come out another of its choosing. Up to six mirrors can be on the map at the same time, and when the monster enters one they select any other one to come out of. Other creatures can enter these mirror portals put just take 1d6 necrotic damage.