Stoneskin

4th-Level Transmutation
Casting Time: 1 action
Range: Touch
Components: VSM($) (diamond dust worth 100 gp, which the spell consumes)
Duration: (C) 1 hour

This spell turns the flesh of a willing creature you touch as hard as stone. Until the spell ends, the target has resistance to nonmagical bludgeoning, piercing, and slashing damage.

At Higher Levels. When you cast this spell using a spell slot of 5th level or higher, you can target one additional creature for each slot level above 4th.

Source: PHB 278, SRD

Changelog

Added upcasting option.
Altered spell school to Transmutation from Abjuration.