Magic Jar

This risky spell allows the caster to transfer his or her mind into that of another creature, trapping the other creature’s soul in a gem (of not less than 100 gp value) that is the material component of the spell and becomes the magic jar. To accomplish the transfer of souls, the magic user must trap his or her own life essence within the jar prior to the transfer. If the transfer fails (e.g., if the targeted creature makes a successful saving throw), the caster’s soul is trapped until it can take over a host or otherwise escape.

The caster can make successive attempts to take over the same host, but no more than one per round. The spell’s range applies to two matters; when the magic user first transfers his or her own life essence into the jar, his or her body must be within the spell’s range of the jar. The range also limits the distance at which the magic user’s soul may later escape from the jar and into another body. After the caster’s soul moves into the jar, his or her physical body becomes inert and lifeless.

The spell represents, in many ways, a contest of will between the magic user and the creature whose body he or she seeks to possess. The caster and the target creature each total their intelligence and wisdom scores (such being calculated or approximated by the GM for a monster). This combined score represents the character’s mental power for purposes of the spell. The two numbers are compared, and the difference is used in two important calculations: the saving throw and the chance for escape. One third of the difference (rounded down) is the modifier on the saving throw, a bonus if the target creature has the higher mental power, a penalty if the magic user’s mental power is higher.

If a creature’s soul is trapped in the magic jar by the caster, it has a chance to escape. If it escapes, the caster’s soul is returned to the magic jar. If the difference in mental power between the caster and the possessed creature is 4 or less in favour of the caster, or is in favour of the possessed creature, the creature can attempt a new saving throw every round. If the difference is from 5 to 8 in the caster’s favour, one saving throw is permitted per turn. If the difference is 9 to 12 in the caster’s favour, the saving throw is made once per day, and if the caster’s mental power exceeds that of the target creature by 13+, the saving throw can only be made once per week.

While the caster is in the magic jar waiting to possess another body, he or she can sense creatures beyond the jar, but not their nature. The jar may be moved from its original location, but not, obviously, by the caster. When the caster possesses another body, he or she gains complete control of its movement and acquires any memories that the body might reflexively recall (how to fly, fight with claws, use innate magical powers, etc). He or she does not gain any knowledge from the creature’s mind, such as languages known or the location of a lair, for the mind is trapped in the magic jar. The caster retains his or her own mind while possessing the other body, so if the body possesses the correct physical attributes the caster can continue to cast his or her spells from within the new body.