Girdle of the Sun's Champion

Wondrous Item (Belt), Artifact, Requires Attunement

While wearing this belt, you gain Resistance to all types of damage, with the exception of Psychic and Necrotic. 

Additionally, your speed is doubled and you gain a flying speed equal to your walking speed. 

The Power of a Million Exploding Suns - As an action, you may call upon the power within the belt to become a god among men and gain the following benefits for 1 minute. After the effect wears off, you gain 1 point of Exhaustion. 

• Your Strength and Constitution scores become 30

• When hit by a spell that deals damage that you are resistant to, you may use your Reaction to absorb the energies of the spell, gaining a number of hit points equal to the damage it would deal if you did not have Resistance. If you are at full health when using this ability, you gain half as many temporary hit points instead.

• You may cast the Wish spell 3 times, with the caveat that any effects produced by the spell only last until your next long rest.

After 1 minute, you may choose to extend this effect, but for every minute after the first, you take an additional point of Exhaustion when it ends. Upon the effect ending, you must make a Wisdom saving throw equal to 12 + the number of rounds you remained under this effect. On a Failure, the Girdle’s Call of the Void effect is activated. 

Call of the Void - Upon failing your saving throw, shadows creep from the Girdle, covering you completely. While under this effect, you gain all the benefits of The Power of a Million Exploding Suns. In addition, you become Immune to Necrotic damage, but Vulnerable to Psychic damage.

While under the effect of this ability, you regard all living creatures as something to be destroyed and must attack or otherwise harm the nearest creatures, regardless of whether they are allies or enemies. At the end of your turn, you must make a DC 20 Wisdom saving throw with Disadvantage to end the effect and regain control. If you’ve taken Psychic damage in the last round, you can make this saving throw without Disadvantage.

As an Action, a character can make a DC 20 Charisma (Persuasion) check, to convince you to see the light. Each time a character is successful, the DC of the Wisdom saving throw to end the effect is reduced by 1. Any characters who attempt these skill checks become your primary targets to destroy. 

(No Design Works on this one, it's just the belt that Marvel's The Sentry wears with the "fantasy clothing" aspect dialed up)