Magus is randomized in Jets of Time. There is a 1 in 7 chance that he'll stay unchanged, but in the other 6 of 7 times, he'll be replaced with a version of another party member. For the purpose of this page, we'll refer to the boss as Magus regardless of which character shows up.

Magus can have his MDef lowered by attacking him with Frog while equipped with the Masamune (not the GrandLeon). Magus is weak to the magic type he casts and absorbs all others. When “Magus risks casting a spell”, he begins charging his ultimate spell, which is dependent on the sprite (see below table). During this time he is vulnerable to all attacks.

Magus's ultimate ability (Dark Matter in vanilla) will be replaced with a different, attack, depending on which party member takes his place.