Rexbolt (レクスボルト Rekusu boruto, also known as Mjolnir in the French version of the games) is the most powerful Thunder magic tome in Fire Emblem: Path of Radiance and Fire Emblem: Radiant Dawn. When cast, a plethora of dark rainclouds will be summoned into battle, whereupon they will charge up a single bolt of lightning. Upon contact with the ground in the immediate circumference if the selected enemy target, the bolt of lightning will diverge and continue to parlay its voltage in four separate streaks. These streaks will then converge together in one massive swoop, culminating into a crescendo of explosions, derived from the pent-up energies contained within the summoned lightning.
In Radiant Dawn, Ilyana is the only character who can wield this tome, owing to the fact that she is the only character capable of achieving an SS rank in Thunder Magic.