Bardock, Zariel' Slave

Agonizing Blast. Bardock add his Charisma modifier to the damage rolls of his Eldritch Blast Cantrip (already calculated).

Devil's Sight. Bardock can see normally in Dim Light and Darkness - both magical and nonmagical - within 120ft from himself.

Dark One's Blessing. When Bardock reduce an enemy to 0 Hp, he gains 18 Temporary Hit Points.

Legendary Resistance (3/day). When Bardock fails a Saving Throw he can choose to suceed instead.

Zariel' Slave (Mythic Trait; Recharges after a Short or Long Rest). When Bardock is reduced to 0 Hp, he doesnt fall unconscious. Instead, he awake his bond with Zariel creating a Fire Dagger as a Pact Weapon and regains all his Hp. When his Mythic trait is active he can use two more attacks listed in the attack box. After Bardock is reduced to 0 Hp again he dies and his soul warpsto Zariel.

Multiattack. Bardok makes two Cantrip attacks or he can cast a spell . When he is in its mythic form he uses also his Pact Dagger attack.

Repelling  Blast. Ranged Spell Attack Roll: +10, 120ft, Hit: 20 (3d10 + 5) Force damage and he can push that creature up to 10 ft straight away from him..

Chill Touch. Melee Spell Attack Roll: +10, 5ft ,Hit: 15 (3d10 ) necrotic damage and it can't regain hp until the end of your next turn.

Pact Dagger (Only Mythic Form). Melee Attack Roll: +10, reach 5 ft/30ft throw. Hit: 9 (1d6 + 5) Piercing damage plus 23 (5d8) Fire damage.

Hurl Through Hell (Recharge 5-6)(Only Mythic Form). When Bardock hits a creature with an attack he can try to instantly transport the target through the Lower Planes. The target must succeed on a DC18 Charisma saving throw or he disappears and hurtles through a nightmare landscape. The target takes 8d10 Pyschic damage and is Incapacitated until the end of your next turn, when it returns to the space it previously occupied or the nearest unoccupied space.  

Spellcasting. Bardock casts one of the following spells, using Charisma as the spellcasting ability (spell save DC 18, +7 to hit with spell attacks):

At Will: Eldritch Blast, Chill Touch, Arms of Hadar (level 5 version), Scorching Ray (level 5 version), Hellish Rebuke (level 5 version), Crown of Madness, Counterspell (Level 5 version), Fear, Hold Person (level 5 version), Mage Armor*
5/Day: Power Word Stun, Finger of Death, Blight, Circle of Death

Shadow Step. Bardock can teleport 5ft from a creature who has been marked by the Vengeance Mark feature during his turn as a bonus action. 

Hellish Rebuke. The cultist casts Hellish Rebuke in response to that spell's trigger, using the same spellcasting ability as Spellcasting.

Counterspell. Bardock can casts Counterspell (level 5 version) in response of another creature spell cast.

Bardock can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature's turn. Bardock regains legendary actions at the start of its turn.

Inchoerent Whisper. Bardock point a creature he can see within 60ft from him forcing it to make a DC18 Wisdom Saving Throw. If it fails he must use his reaction to make an attack to the nearest ally. If the are no creature within his reach he tries to end himself taking 1d10 + that creature strenght modifier.

Cantrip Attack. Bardock cast a Cantrip Attack against one enemy he can see.

Blessing of the Dark One. Bardock casts one Eldritch Blast against one prisoner in the Arena killing him instantly., after that Bardok gains 18 Temporary Hit Points

If Bardock Mythic trait is active he uses the options below as legendary actions replacing his previous actions. He can use the options below for 1 hour after using Zariel' Slave trait.

Vengeance Mark. Bardock choses a creature he can see within 60ft from him marking it for a death blow. That creature becomes vulnerable to fire damage and Bardock can always teleport 5ft from it as a bonus action during his turn. After that creature is hit by an attack the Mark expires and that creature can immediately take an action.

Cantrip Attack. Bardock cast a Cantrip Attack against one enemy he can see.

Fire Crescendo (Cost two actions). Bardock choses a creature he can see within 60ft from him setting him on fire. After 2 turns that creature explodes taking 6d10 unless he successfully takes a Magic Action to undo the crescendo (DC 15 Arcana).