Hoard armor

Hoard armor was a defensive spell that could only be cast by dragons.

Effects
When cast within the dragon's lair, unsecured treasure was drawn into a swirling cyclone around the dragon, creating a protective barrier. Only gems and items made from copper, electrum, gold, platinum or silver were drawn into the barrier. An individual piece of treasure could not be more than in weight and had to be within  of the dragon. The cyclone of treasure completely surrounded the dragon except for the face and claws, allowing the dragon to cast further spells. The dragon was able to slowly move around their lair. The spell was vulnerable to dispel magic.

Casting
In addition to a verbal component, the spell required a material component. About 1% of the gems and precious metals used in the spell were consumed.