Curse Of Rage

All of your hatred and rage has cursed you with a forceful, consuming wrath. The Demon of Anger gnaws at your mind and body, twisting you into both a survivor and a weapon.

This curse grows stronger the more you embrace your rage. Depending on the number of levels you have in Barbarian, you gain the following major benefits and minor benefits.

Level 1: Mindless Hatered

All Wisdom and Intelligence saving throws you make while raging have disadvantage, and you can't be frightened while raging.

Level 2: Merciless
 
If you try to willingly spare a creature, you must succeed on a Wisdom saving throw (DC 15), or be guided by your Demon of Anger to relentlessly and recklessly pursue the target. For the next minute at the end of each of your turns you can repeat the saving throw, but during this duration you are charmed by your Demon of Anger and must pursue what it demands, which is normally to kill the target your fighting, otherwise if you keep failing saving throws it lasts until the creature is killed. 

Level 3: Relentless Pursuit

If an enemy flees, while raging Z is compelled to chase them. He cannot willingly turn to another target until the first is downed, even if it leads him into a trap or is obviously trying to get Z to follow them.

Level 4: Unending Anger

You can no longer willingly end your rage as a bonus action, and while raging you have disadvantage on all Intelligence, Wisdom, and Charisma saving throws.

The 3rd-level spell Remove Curse does not end this effect. Instead, it forces the Demon of Anger into a manifested state for 1 hour, appearing as a shadowy, spectral version of your upper body tethered to you.

• The demon acts as a separate hostile creature, which can be attacked and destroyed.

• If reduced to 0 hit points, the demon retreats and reforms inside you after a long rest. Unless the final strike done to it was with Force, Radiant, by a critical hit, then the demon is destroyed. And consult your DM about slightly remaking your character

The only way to permanently end this curse is to slay the Demon of Anger while it is manifested.