Cryostasis

You encase a willing creature in a cocoon of ice, putting it in a state of suspended animation until the spell ends. The creature is unconscious until the spell ends. Time does not pass for the creature while the spell is active.

The icy casing is immune to all damage. The spell ends if the ice is affected by a disintegrate spell. Ability checks made to dispel this spell via dispel magic are made with disadvantage. Spells and other effects are unable to pass through the ice to affect the creature inside.

Upon casting this spell, you can designate an amount of time after which the spell will end on its own, safely releasing the encased creature.