Enercell Stone

The Enercell Stone is the product of The Academy Of Arcane Studies. It allows the storage of essence to be used by everyone on Terra and can be built into devices to act as rechargeable essence batteries. The Enercell Stone has become sort of a profit center for the Academy. It is very expensive at a cost of $1000 per single power point worth of storage. The Enercell Stone has a few slight drawbacks. If it is ever fully drained it is destroyed and becomes dust. If it is over charged it explodes, doing Blast spell damages equal its power point rating. Enercell Stones act oddly when in close proximity to each other, the larger of any two stones pulls essence from all smaller stones nearby and can easily become overcharged. The smaller stones can become totally depleted and turn to dust. Casters, to counter these issues, only carry stones of matched size and keep them separated from each other.   Since it takes very little essence (power points) to maintain a spell once it has been cast, the Enercell Stone can keep a spell going for long periods of time, months or even years after original casting.   Enercell Stones come in the following sizes:   5 PP (size 1 cm diameter sphere) Cost $5000 at the academy. Expect markup at retail locations.
10 PP (size 4 cm sphere) Cost $10,000 at the academy. Expect markup at retail locations.
20 PP (size 8 cm sphere) Cost $20,000 at the academy. Expect markup at retail locations.
50 PP (size 20 cm sphere) Cost $50,000 at the academy. Rare to find at retail locations. Often used to power floating wagons.
100 PP (size 40 cm sphere) Bigger than a basketball (weighs in excess of 1000 lbs). Special order from the academy and installed only by the academy High Magi. Commonly found in Arcane Siege Weapons like the Fireball Catapult, Lightning Bolt Ballista, or the Thunder Strike Trebuchet.