The Singularity

Most denizens of the galaxy think that the ravenous chasms known a black holes are simply portals to the Void, formed from the collapse of particularly large stars. This theory brings them a sense of understanding to these dangerous galactic phenomena, and imparts a sense of control and comfort to those who would otherwise despair in the face of such a terrible, destructive force of nature. 

However, the small group of warlocks who draw their power from these black holes know better: The Singularity is intelligent, malevolent, and above all, hungry. 

Hunger of the Void

Starting at first level you can channel the ravenous hunger of The Singularity to absorb energies directed at you. When you are damaged by an effect or attack that deals damage or a type other than bludgeoning, piercing, or slashing, you can use your reaction to reduce the damage you take equal to your Charisma modifier. When you do so, you gain temporary hit points equal to your Warlock level. 

Brink of the Void

Starting at 6th level, you can induce terror and despair by showing others the truth of the Void as an action. Each creature within 30 feet of you that can see you must succeed a Wisdom saving throw or be frightened of you for 1 minute. If a frightened creature ends its turn in a location where it doesn't have line of sight to you, the creature can make a Wisdom saving their, ending the effect on a successful save. Once you use this ability, you can't do so again until you finish a short or long rest. 

Accretion Disk

Starting at 10th level, whenever you use you Hunger of the Void ability, you can surround yourself with a working disc of damaging energy. For a number of turns equal to your Charisma modifier, or until you use this ability again or dismiss this effect on your turn (no action required), any creature that starts its turn within 10 feet of you takes damage equal to your Warlock level of the type you avoided. 

Event Horizon

Starting at 14th level, as an action, you can summon a 20-foot radius sphere of pure Voidstuff, centered on yourself. The first time a creature enters the area in its turn or when it starts its turn there, it must make a Strength saving throw. On a failed save, it takes 7d6 necrotic damage and is restrained until the start of its next turn. On a successful save, the creature takes half as much damage, and moves through the area as difficult terrain. You can concentrate on this effect, as you would a spell, to maintain this sphere for up to 1 minute. 

I've you use this ability you can't do so again until you finish a long rest. Additionally, you have an advantage on checks you make to control spheres of annihilation.