Ring of Borrowing

This ornate gold ring with a single large ruby in the middle. The ring it self is not innately magical, but the ruby in the middle does give off a faint arcane hum. When casting a spell with a material cost of any gold amount (example: if the caster wants to cast resurrection, the 1000gp diamond) the ruby can be used instead. In three days an infernal imp appears demanding payment. This imp works for an infernal loanshark, a devil named Octivarius. If you pay the imp in full, the exact amount of gold for the spell plus a 3% interest, the ruby is restored and can be used again. Each time the ruby is used up the price must be payed.

Notes: spellcaster