Wendigo Goblin God-Lich

Special Trait Name. Ancient spell-casting.

Spellcasting. The Wendigo Goblin God-Lich is an 18-level spellcaster. Its spellcasting ability is int (spell save DC 20, +8 to hit with spell attacks). The Wendigo Goblin God-Lich has the following Warlock spells prepared:
Cantrips (at will): Eldrich Blast, Mind Sliver, Toll the Dead, Frostbite
1st level (6 slots): Hellish Rebuke, Hex
2nd level (5 slots): Misty Step, Shatter
3rd level (4 slots): Counter Spell, Summon Lesser Demons
4th level (3 slots): Blight, Summon Greater Demon
5th level (2 slots) Infernal Calling, Synaptic Static 

Action Name. Ancient Goblin fighting.

Action Melee Attack. Melee Weapon Attack: +6 to hit, reach 5 ft., # target. Hit: 28 (8d10 + 4) necrotic damage. 
Weapon: Decaying Great club: While in possession of an attuned wielder, this great club's damage becomes necrotic. 

Action Ranged Attack. RangedWeapon Attack: +#4 to hit, range 10/60 ft., 1 target. Hit: 23 (5d8 + 5) Necrotic damage.

Silent casting - Can cast a cantrip or level 1 spell that requires a verbal component as if there was no verbal component.
Life Drain - Can drain 3d4 health from a creature it can touch. (you can use this as many times as the proficiency bonus allows)

Reaction Name. Hellish rebuke
Opportunity attack, Hide, Improvised weapon, 

Enter the description for how legendary actions work for your monster here.

Legendary Action Name (Costs # Actions). Enter the description for your legendary action.

While in the Main hall, the Wendigo Goblin God-Lich can sacrifice HP to special summon a Boneless that has been slain and is part of its phylactery.

Mythic Action Name (Costs 3 Actions). 
The Wendigo Goblin Lich-God can sacrifice up to 50 HP to special summon a Boneless in a location it can see within 40ft if itself.