Champion of Vayne

Storm Aura
As a bonus action, the  Champion can go into a rage and manifest a 10 ft. arura extends 10 feet in every direction, but not through total cover

Each hostile creature must make a Dexterity saving throw. The target takes 7 (2d6 ) lightning damage on a failed save, or half as much damage on a successful one.
At the start of the champion's turns, any hostile creature within 5ft must repeat the save.

Blood Frenzy. The warlock has advantage on melee attack rolls against any creature that doesn’t have all its hit points.

Eldritch Maul Melee Attack (2 attacks) : +9 to hit, reach 5 ft. Hit: 14 (2d6+ 7) piercing damage plus 5(1d8) Necrotic damage

Sentinel Attack If the Champion hits with an opportunity attack, the target's movement speed is reduced to 0 until the start of their next turn