Power Symbiont

A power symbiont looks just like a dab of swamp fungus, dark brown at rest and rust-colored while feeding on magic. It is very small, and once it grows to twice its normal size it splits asexually.

Spells cast at a power symbiont rebound on their source at full strength. That can actually help an infested ship: if an enemy vessel's spell catches a symbiont in its area, the spell flies back at the attacker, and neither the caster nor that ship gets any Dexterity or starhelm rating bonus on the save.

Starship crews loathe them, since they do nothing but sap the power of magic items aboard. They have turned up on planets too, souring some regions on starfaring altogether. They form no society; they gather only where there is enough magic to feed them, and leave an item once it is spent.

Symbionts sense magical auras across the void between worlds, but they move so slowly that they can only wait for a passing ship's gravity to sweep them up. Aboard, they creep at a movement rate of 1/4 toward any aura within 20 feet, switching course only for a stronger one, until they reach the most tempting item and attach to it.

Feeding, it saps one charge each round. Once the item is drained of charges, the parent sends out 1d8 quarter-inch offspring to find more magic, then dies and hardens within a day into a brown lump. Offspring that find nothing within a week cross the ship's gravity plane and fling themselves back into the void. Any that drift into the flame-sea perish instantly.