Valanir's Virulent Veil

An explosion of corrosive mist explodes around a creature of your choice, leaving a shifting coating of protective acid surrounding the target.

When the spell is first cast, each creature other than the target within a 20-foot-radius sphere of the target must make a Dexterity saving throw. On a failed save, a creature takes 18d4 acid damage, or half as much damage on a successful one.

For the duration of the spell, whenever a creature within 10 feet of of the target hits them with an attack, the acid splashes that creature, dealing it 4d4 acid damage. In addition, Any nonmagical weapon made of metal that hits the target corrodes. After dealing damage, the weapon takes a permanent and cumulative −1 penalty to damage rolls. If its penalty drops to −5, the weapon is destroyed. Nonmagical ammunition made of metal that hits the target is destroyed after dealing damage.

This spell automatically corrodes nonmagical objects surrounding the target that are not held or equipped. Over the course of the spell, it can completely dissolve wooden objects, corrode through 2 feet of stone, and eat through 2-inch thick metal. The surface the target is standing on is unaffected.

At Higher Levels. When you cast this spell using a spell slot of 7th level or higher, the initial damage increases by 4d4 for each slot level above 6th.