Warlock of the lich

Eldritch Mind  The warlock has advantage on CON saving throws to maintain concentration on a spell.

Spellcasting The warlock is a 16th level spellcaster. Its spellcasting ability is CHA (spell save DC 17, +9 to hit with spell attacks). It regains its expended spells when it finishes a short or long rest. All spells  cast in this way are cast at the 6th level. It knows the following warlock spells. 

At-will: booming blade, disguise self, mage armor, minor illusion,  prestidigitation 

3/rest: detect thoughts, dispell magic, hex, hold monster, hold person, mirror image, sickening radiance, synaptic static

1/rest: etherealness, soul cage

Multiattack
The warlock attacks three times with its eldritch burst or paralyzing touch.

Eldritch burst Ranged spell attack: +9 to hit, reach 120 ft, one target. Hit: 11 [roll]1d12+5[/roll] force damage. The warlock can also choose to  push the creature up to 10 feet away from them in a straight line.

Paralyzing touch Melee Attack Roll: , reach 5 ft. Hit: 15  Cold damage, and the target has the Paralyzed condition until the start of the lich’s next turn.