Cryogenesis

You encase yourself or a willing creature in magical ice, forming a suit of frost-like armour that provides significant protection and imbues the target with icy powers. The target gains temporary hit points equal to 60 + your spellcasting ability modifier. These temporary hit points absorb all damage types except psychic. At the start of each of the target’s turns, the shell regenerates temporary hit points equal to your spellcasting ability modifier, up to the original maximum, as long as the caster maintains concentration. Once the armour breaks, the spell ends.

While encased in the armour, the target gains resistance to fire damage as well as slashing, bludgeoning, and piercing damage from nonmagical attacks, as well as immunity to cold damage and the frightened condition.

Melee weapon attacks made by the target deal an additional 2d8 cold damage. Additionally, the target can unleash a burst of freezing energy as an action. Each creature within 15 feet must make a Constitution saving throw, taking 4d10 cold damage on a failed save and having their movement speed halved for 1 minute. On a successful save, a creature takes half damage and is not slowed. Once this ability is used, the target must roll a d6 at the start of each of its turns; on a roll of 5 or 6, the ability recharges.

The frost armour creates difficult terrain wherever the target moves, leaving a trail of ice in its path. Any water within 10 feet of the target freezes solid. When the spell ends, whether due to duration, the depletion of temporary hit points, or loss of concentration, the encased creature suffers the effects of a bonechill as the target becomes vulnerable to cold and fire damage. These effects last for 1 hour.