Medallion of Cursed Rage

A pendant that has a moving eye in the middle. Eight wide triangles form the edge of the pendant, being spaced apart equally. The eye in the center has a blue iris and usually stares straight ahead, occasionally averting its gaze. A simple metal chain allows for someone to hang the pendant around their neck. While the medallion is active, the eye in the center will become blood-soaked and sporadically move as if in a frenzy.
Whenever someone equips the pendant, the chain will fade and it will attach itself to whatever surface it comes in contact with, may this be armor or skin. To dequip the medallion, dispel magic must be used, or the eye in the center must be stabbed with a sharp object, however, this will break the pendant. In either case, the pendant will detach itself from the material and the chain will reappear.
When enraging or by using a bonus action while enraged, you may spend a quarter of your remaining health (rounded up) to enter cursed rage for three turns. While under the effect of cursed rage, you gain the following effects:

• Your Movement speed is increased by 10
• You can make one additional attack each turn
• When having advantage on an attack, you may choose to knock the target back. This knockback is equal to 5 feet, plus 10 feet per size you are above the target. If a knocked-back target collides with something, they take physics damage equal to half the distance they got knocked back, rounded down. If a target collides with another creature, the damage is split between them. You cannot knock back enemies of a size greater than yourself.