Xephy's Arcanovore

You drink the spell components from the small chalice. A coruscating beam of black shadow connects you to a creature that you can see within range that is capable of casting spells, forming a sustained arc of negative energy between you and the target. You and the creature make an Charisma saving throw versus yours or the creature's spell save DC whichever is higher. A failure results in 18d6 Psychic damage and losing the use of spell slots up to a cumulative 6th-level spell slot in spell levels. On a success, you or the creature take half the damage and lose the use of spell slots up to a cumulative 3rd-level spell slot in spell levels. The owner of the spell slots will choose which slots to lose via this effect.

Shared Suffering. For the duration of the spell yours and the target's movement is halved and you can locate each other telepathically despite obscuring effects like Darkness or Invisibility or even solid barriers.

Insatiable Hunger. You may choose spell slots that exceed the spell level required. For example: you may choose a 7th level slot if you no longer have any 6th level slots left or choose to lose two slots of 2nd level, and one slot of 3rd level, but not less than the spell levels required of you to lose. If you no longer have enough spell slots to cover the required loss in spell levels, you expend as close to the number of spell levels you can and take an additional 3d6 Psychic Damage for every spell level you could no longer lose a spell slot for. This added damage cannot be resisted or prevented.

Unquenchable Thirst. The spell slots lost in this manner may not be regained through any other means other than by a Greater Restoration or a Wish spell.

Ravenous Gluttony. On your next turn you may use your action to repeat the effect again. The spell ends if you take a different action than maintaining the spell. The spell also ends if either you or your target move out of the spell's range or are on separate planes of reality.

Unending Feast. Cover or lack of sight has no effect on this spell once cast. Damage dealt to the caster from any of this spell's effects do not affect the concentration to keep this spell active. This spell is not subject to a Counterspell, Dispel Magic or any antimagic effects such as Antimagic Fields or the main eye cone of a Beholder.

Special: This spell does not affect spell-like effects such as psychic powers created by mindflayers or natural magics cast at will by supremely magical creatures such as dragons. Such creatures though non-reliant on spell slots still suffer the damaging effect of the spell on a failed save but no damage through being unable to expend spell slots as detailed under the spell's 'Insatiable Hunger' effect.