Helm Bomb (Magic Explosive)

The arcane sell very few helm bombs. These large, not-easily-concealed devices are simply normal-looking helms that can somehow “turn on” within the spelljamming field of another magical power source. In this rare instance, operating multiple power sources would result in the ship upon which the helm bomb was placed being torn apart. This occurs even if the controller of the original power source attempts to exactly match the direction and intensity of the thrusts.
The devices' warring power fields force them apart, destroying the ship and firing the two sources away from each other in random directions and speeds. They continue to operate until power is removed or exhausted. In the case of the original power source, that may be within a round. If it is a helm, the spelljammer suffers 2d4 points of damage while the helm smashes its way out of the ship, and must save against death magic or go into spelljammer shock (detailed in the Spelljammer® boxed set). If this knocks the spelljammer out, the helm ceases to spelljam, although it will probably be well away from its parent ship by then and moving fast. The helm bomb rushes on through space, a dwindling but dangerous space missile (taking the ship, or a piece of the ship with it), consuming its own material for power. It cannot be stopped or salvaged.
The bomb typically consumes itself in 50 days minus the ship's tonnage (a shipless bomb weighs 1/4 ton). Ships over 50 tons use up the bomb in 1d4 turns. A helm bomb must be brought onto a ship (though it need not be fastened down or even taken into an interior area). If it is turned on when no other magical power source is “on,” it does nothing except act as a self-powered helm that eats itself up and then collapses, doing 1d6 hull points of damage (and 1d6 points of damage per round to anyone sitting upon it as it operates). Its bomb effects occur only when another power source is operating. If the bomb is already “on,” a second source cannot be activated, and no ship breakup occurs. This way, it can be used as a one-shot hijack power source, to prevent control by the ship's legitimate helm.
Activating a helm bomb as a power source requires that a living being sit in the helm. The being need not have magical or spelljamming ability, but must sit there to will the helm into action. Such a being can get up as soon as she sets a course direction, and thereby avoid any damage as the helm bomb consumes itself. However, if used as a bomb, the activator is on it when it flies apart and suffers the same 2d4 points of damage as a helmsman aboard the legitimate helm. An adroit activator can hurl clear an instant after engaging the bomb, to avoid being pulled out of the ship, but cannot avoid suffering damage. Note that this provides a kamikaze (or at the least, very dangerous) method for intruders to damage, destroy, or steal enemy ships in close quarter combat. 
Category:Encyclopedia Magica Magic Items
Category:Magic Items
Category:Magic Explosive Devices
Category:Magic Weapons