Vessel of Dreams

Wondrous item, very rare (requires attunement)

This waterskin is always filled with a strange, mercurial fluid.

As an action you can pour this liquid down the throat of a creature within 5 feet of you that is engaged in a long rest and has not drunk from the vessel within the last 24 hours. The target must attempt a DC 15 Wisdom saving throw. On a success, the target is gifted with dream of either rejuvenation or triumph (your choice), which lasts for the duration of the rest.

A creature experiencing the rejuvenating dream gains 4d10 temporary hit points when it awakens.

A creature gifted with the triumphant dream gains a powerful boon when it awakens. When a creature with this boon makes an attack roll with advantage, it may roll three dice instead of two, choosing the highest result from among the rolls.

These effects last for 8 hours.