The relic Soul of Thamasa (called Gem Box in the SNES translation) grants the wielder the ability of Dualcast, but disables the use of summoning espers. Originally, it could only be acquired atop the Cultists' Tower, but in the Advance and smartphone remakes, it can be stolen from Glutturn. Thamasa is a town founded by disgraced mages and populated by their descendants, and one of the only places left in the world where magic is still practiced; the item's name alludes to the town.