Chaoswalker

Dark Fortitude. If damage reduces the chaoswalker to 0 hit points, it must make a Constitution saving throw with a DC of 5 + the damage taken, unless the damage is from a critical hit. On a success, the chaoswalker drops to 1d10 hit points instead.

Spellcasting. The chaoswalker is a 14th-level spellcaster. Its spellcasting ability is Intelligence (+8 to spell attacks, save DC 18). The chaoswalker has following wizard spells prepared:

Cantrips (at will): chill touch, shocking grasp, produce flame

1st level (4 slots): absorb elements, burning hands, cause fear, chaos bolt

2nd level (3 slots): darkness, gust of wind, dust devil

3rd level (3 slots): animate dead, thunder step

4th level (3 slots): fire shield, ice storm

5th level (3 slots): control winds, flame strike

6th level (1 slots): bones of the earth, chain lightning

7th level (1 slots): fire storm, finger of death

Chaos Burst. Melee Spell Attack: +6 to hit, reach 5ft., one target. Hit: 1d10 lightning damage. Upon fail, deal 1d6 damage to self. 

Elemental Touch. The chaoswalkers dark elemental energy springs forth from its hands. The chaoswalker chooses a target within 10ft., casting two of the following spells at random. To choose each spell, 1d4.

1. Chill Touch 

2. Shocking Grasp 

3. Burning Hands

4. Gust of Wind