Amulet of Ultimate Power

The Amulet of Ultimate Power is a legendary necklace with a small stone suspended in it. Once the amulet is in a non-undead creature, the stone will choose its wielder based on the creature's rage and fury, electing one creature and only one capable of using the amulet's powers.

The Amulet has 5 Rage points, in addition to your actual number of rage points as a Barbarian. You can use an action to expend a number of rage (RP for short) points and produce one of the following effects (you can only produce one effect per combat).

Strenght of Titans (4 RP). As you rage in your action, you can choose to use this feature and gain the strenght of titans as long as you are raging. Any melee attack that you make using this feature gives you a +5 attack bonus and an extra 3d8 damage of the type made by your melee attack. +2 in the Exhaustion roll. 

Speed of Light (5 RP). When you choose to use this feature as an action, your speed doubles until your next turn. +3 in the Exhaustion roll. 

Bellator (7 RP). Any nonmagical attack that is made by you until your next turn have advantage on attack rolls made with martial weapons. Also, any attack that hits, hits as a critical hit with an extra 4d8 damage of the type used by the nonmagical weapon. +5 in the Exhaustion roll. 

Elementum Chao (8 RP). You suddenly is consumed by elemental energy, which transforms your body in an extraordinary elemental generator. Choose fire, cold (water), lightning or force (air or earth). Choose a target creature and make an attack roll against it with advantage. On a hit you suddenly appear in front of the creature as if you had teleported and punch it with the element you have chosen. The creature must make a DC 17 Constitution saving throw, taking 6d10 damage of the chosen type on a failed save and half as much damage on a successful one. +6 in the Exhaustion roll. 

Divina Virtute (10 RP). You suddenly teleports close to a creature of your choice, automatically hitting it with divine energy. The creature must make a DC 20 Constitution saving throw, being thrown 15 feet away from you and taking 6d8 radiant damage on a failed save and half as much damage on a successful one. Suddenly the creature explodes in divine power, taking an instant 7d12 radiant damage. You instantly fall uncounscious. +7 in the Exhaustion roll.

When all rage points are spent (including your current rage points as a barbarian), you must roll a d12 and use the modifiers granted by the effects produced, therefore gaining a number of levels of exhaustion based of the result of the dice [see Results at the end of the combat at the end of this item's description]. The amulet regain all spent rage points after a long rest and half as much points (rounded down) after a short rest.

 Results at the end of combat: 

• 1-2: First level of Exhaustion.
• 3-4: Second level of Exhaustion.
• 5-6: Third level of Exhaustion.
• 7-8: Forth level of Exhaustion.
• 9-10: Fith level of Exhaustion.
• 11-12: Sixth level of Exhaustion. (make a DC 15 Constitution saving throw. On a successful save, you make the death saves with advantage)

Notes: spellcaster, but can only be used by a barbarian.