Valik

Infernal Scythe. All of Valiks attacks are magical and deal an additional 4d8 necrotic damage. This is included in the damage done with his scythe. 

Dragonmark of Cataclysm. Once per turn Valik can activate his Dragonmark. 

Spellcasting. Valik  is a 20-level spellcaster. Its spellcasting ability is [Cha] (spell save DC 21, +14 to hit with spell attacks). Valik has following Wizard spells prepared:

(Earthquake, Feeblemind, Power Word Stun, Fire Storm, Gate, Chain Lightning, Meteor Storm)

Magic Resistance. Valik has advantage on saving throws against spells and other magical effects. 

Overwhelming Presence. Enemies within 15ft of Valik must make a DC 18 Charisma saving throw or fall prone as they kneel on the ground in reverence. 

Multiattack. Valik makes two scythe attacks. 

Scythe. Melee Weapon Attack: +14 to hit, reach 5ft., one target. Hit: 20(4d8 + 8)+ 16(4d8)necrotic damage. 

Hell Spikes. RangedWeapon Attack: +8 to hit, range 30/120 ft., 3 target. Hit: 22 (3d12 + 8) fire damage + 12 (4d8) necrotic damage

Audacity. When Valik is the target of a melee attack, he can force the attacker to make a DC 18 Wisdom saving throw. On a failed save the attacker must choose a new target for the attack. 

Valik has three legendary actions choosing from the options below. Only one legendary action can be used at a time and only at the end of another creatures turn. He regains spent legendary actions at the start of his turn. 

Trample Underfoot (Costs 2 Actions). Valik imposes his will upon his foes and forces them to bow before him. All enemies within 30ft must succeed on a DC 18 Charisma save or be forced prone. Standing up from being prone requires half of movement. 

Cataclysm(Costs 2 Actions). Valik casts a spell from his Dragonmark. 

Scythe(Costs 1 Action). Valik makes an attack with his scythe.