Vase of the Obyrith

Wondrous Item, artifact, requires attunement

The Obyrith were the progenitors of the Tanar'ri, the modern demons of the Abyss. They existed before the gods and before creation, some planeswalkeres believe them to be the purged and unwanted aspects of AO, others believing their origin to lie beyond realmspace.

Vessel of Chaos

Such was the chaos of the Obyrith that even studying this vase is enough to ruin the psyche of any creature. Any attempts to identify this case requires a Charisma saving throw with a DC equal to the number of hit dice of the identifier, with a minimum DC of 20. A failure results in any form of long term madness determined by the DM and the effects of a feeblemind spell. If a creature attempts to attune to this item without identifying it, they must still make the saving throw, though it is made at disadvantage, the DC is calculated by adding the number of hit dice of the identifier to two times the constitution modifier of the identifier, with a minimum DC of 25.

While attuned, the user makes Wisdom saving throws at disadvantage, and its Charisma score increases by 4 to a maximum of 30.

Prison of Chaos

As an action, the wielder may make a DC 20 Charisma check and remove the lid from this vase. Failing this check causes the wielder to become the target. On a success, the wielder chooses one target it can see, forcing the target to make a DC 25 Charisma saving throw or be pulled, bodily and spiritually into the vase. Any creature grappling the target may use their reaction to make a Charisma of Wisdom check contested by the target. For every contest the target fails, the target takes a -1 penalty to the Charisma saving throw. A creature pulled into the vase cannot escape unless the lid to the vase is removed. The vase can hold one creature at a time.

Ark of Salvation

A group of up to 5 creatures may take 10 hours to perform a ritual of banishment detailed on the vase's surface. The ritual requires 100,000 gold pieces worth of diamond dust and the ritual sacrifice of vitality. The hit point maximum of any creatures participating permanently lowers by 20d8 and the constitution score of any participant is lowered by 4. The creatures participating make a Charisma (arcana) check throughout the 10 hour ritual with a combined DC of 80. A failure means the ritual is unsuccessful, though the sacrifices are consumed. 

A success banishes the vase and any creature held within to a reality beyond existence, beyond AO, and beyond the far realm. A creature may still have slight influence on realmspace of they possess the requisite power, but a successful return would require the inhabitants of the space the vase is sent to perform the above ritual, with an infinitesimal chance that the vase is sent to this universe as opposed to the infinite other possible target universes.