Aagowrath, Scourge of Helvetia

Sunlight Sensitivity. Aagowrath has disadvantage on attack rolls and saving throws in sunlight. While in sunlight, he loses his resistance to all damage. 

Incorporeal form. Aagowrath has advantage on stealth checks in darkness, he can move through spaces as small as an inch without expending movement. Aagowrath has resistance to all damage. 

Experienced in death. When bloodied, Aagowrath has +3 to dex and wisdom, and he can take two reactions each battle round. 

Spellcasting. Aagowrath a 10-level spellcaster. Its spellcasting ability is Intelligence (spell save DC 17, +7 to hit with spell attacks). Aagowrath has following spells prepared:
Cantrips (at will):  chill touch, poison spray, toll the dead
1st level (4 slots):  false life, mage armor, magic missile, ray of sickness
2nd level(3 slots):Death armor, ray of enfeblement
3rd level(3 slots): counterspell, summon undead
4th level(3 slots): blight, backlash
5th level(2 slots):Raise dead, contagion

Multiattack. Aagowrath makes one Wraith Talon and Life Stealer attack. 

Wraith Talon. Melee Weapon Attack: +7 to hit, reach 10 ft., 1 target. Hit: 24(4d8+4) necrotic

Life Stealer Hexblade. Melee Weapon Attack: +7 to hit, reach 10 ft., 1 target. Hit: 10(1d10+4)slashing. When Aagowrath attacks a creature with this magic weapon and roll a 20 on the d20 for the attack roll, that target takes an extra 15 Necrotic damage if it isn’t a Construct or an Undead, and Aagowrath gains Temporary Hit Points equal to the amount of Necrotic damage taken.

Wraith Claw. Melee Weapon Attack: +7 to hit, reach 10 ft., 1 target. Hit: 7 (2d6) slashing damage + 9(2d8) necrotic. He can only make this attack if cast a spell as his main action.

Counterspell. Aagowrath attempts to interrupt a creature in the process of casting a spell. The creature makes a Constitution saving throw. On a failed save, the spell dissipates with no effect, and the action, Bonus Action, or Reaction used to cast it is wasted. If that spell was cast with a spell slot, the slot isn’t expended. 

Backlash. Aagowrath wards himself against destructive energy, reducing the damage taken by 4d6 plus your spellcasting ability modifier.I f the triggering damage was from a creature within range, you can force the creature to make a Constitution saving throw. The creature takes 4d6 Force damage on a failed save or half as much damage on a successful one.

Aagowrath has 3 legendary actions

Wraith claw (Costs 1 Actions). Aagowrath uses his Wraith Claw attack.

Life Stealer(costs 2 actions). Aagowrath uses his life stealer attack.

Lesser cast(costs 1 action). Aagowrath casts a 1st level spell without expending a slot. 

Greater Cast(costs 2 actions). Aagowrath casts a 2nd level spell without expending a slot. 

Prepare for battle(costs 1 action). Aagowrath regains a reaction if he has none. 

Mythic Action Name. Enter the description for how mythic actions work for your monster here.

Mythic Action Name (Costs # Actions). Enter the description for your mythic action.