Base Class: Barbarian
Some Barbarians didn't choose the path of rage... something choose it for them. Wretched Mind Barbarians are a people who made deals with beings of great power in order to fulfil their own hopes and ambitions but their mind couldn't handle the knowledge/power gifted to them and their minds were shattered. In an attempt to save their deal a greater power restored their mind but it didn't go without a trace, the dark power has altered them.
Release Insanity
Starting when you reach 3rd level you begin to learn to harness, through your patron, the insanity that plagues you. While not raged you gain access to the Eldritch Blast cantrip and Charisma is your spell modifier for this, if obtained through this subclass only 2 beams can be accessed at later levels. While raging your weapon attacks deal force damage instead of their normal slashing/bludgeoning/piercing damage. (If your weapon deals any other type of damage it would continue to use that damage instead of force)
Bomb of the Demented
Beginning at 6th level when you drop below half of your hit point maximum you can choose to release a surge of Eldritch Energy against the creature that attacked you, if you do so you go drop to 0 hit points and deal force damage to the target equal to to half your hit point maximum rounded down + the damage you took to drop you below half of your hit point maximum. If the damage is more than your hit point maximum then you have 1 failed death save.
Inflict Maddness
Starting at 10th level when you land an attack on a creature and deal damage to it you can invoke your patron to inflict some of your madness on it. After the creature takes the damage you can from your weapon and is still alive you can roll 2d6 force damage and choose to inflict the extra damage onto the creature. If you do you also take the damage. This trait can only be utilized while raging. Can be activated once per turn. The damage increases to 3d6 at 15th level and 4d6 at 20th level.
Harnessed Control
Starting at 14th level when you use your bomb of the demented you no longer go down unless the damage you deal goes over your maximum hit points, even then you have normal death saves.