Ring of Elemental Transmogrification

A magical ring recovered from The Professor by the Dwarf Thoven. The setting of the ring is highly crafted bronze, set with four gems: a sapphire, an emerald, a ruby, and a diamond.

When worn, the Ring of Elemental Transmogrification allows an arcane spell caster to alter one elemental type for another as a swift action when casting a spell. This ability uses charges equal to the spell's level. All other spell effects, metamagics, etc. remain unchanged. For example, changing an Acid Arrow to a Lightning Arrow requires 2 charges, while turning a Fireball into an Acid Ball would take three. Cantrips use one-half of a charge.

The ring is a charged magical item, capable of holding up to 5 charges at a time. Charges are refilled by sacrificing arcane spell levels equal to the number of charges to be regained, with 3 cantrips equaling one charge.