Arcane Cannon

The cannon deals 6d10 points of damage on a successful hit. Add your tier to the cannon's hardness and your tier × 5 to its hit points. Its conductive property can channel any spell with a range of touch (you have to expend only one spell for this, not two). You may cast a spell with an energy descriptor on the cannon. If you do, for a number of rounds equal to the spell's level, half the cannon's damage is untyped damage and the other half is energy damage of the spell's type. Casting a spell with a different energy descriptor onto the cannon replaces its current energy type with that of the new spell.