Corrosive Touch

Make a melee spell attack against a creature. On a hit the target takes 3d6 acid damage and if they are wearing non-magical armor it begins to corrode. Alternatively, you may target a targets metal weapon instead of its armor. As an action on your turn as long as this spell persists you may repeat this effect. If you hit armor or a weapon that has been hit before then that armor suffers a -1 to AC and the weapon suffers a -1 to damage. If the AC of the creature is reduced to 10 the armor is destroyed, and if the weapon suffers a cumulative -5 to damage rolls then the weapon is destroyed

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d6 for each slot level above 3rd.