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. After Magus fades in, you are able to open the menu if you would like to adjust your equipment to defend against the correct element.

Magus's Magic Defense can be lowered by attacking him with Frog equipped with either the Masamune or Grand Leon (Grand Leon support was added in the 3.2 beta). Each time he is damaged, he will cast a spell to indicate a barrier change: the element of the spell he casts (it will be Lightning 2, Ice 2, Fire 2, or Dark Bomb) becomes his only vulnerability and he will absorb all other elements. He will remain vulnerable to physical attacks throughout. On his turns Magus will also cast Geyser (damages the party and inflicts HP Down) or attack single party members with his weapon.

When his HP is at 50%, he will change phases. The earliest indicator of this is that after he takes damage he won't counterattack. His barrier will still be up until he casts Magic Wall (“Magus risks casting a spell”). After this he is vulnerable to any type of damage. However, on his next turn, he will unleash his ultimate move (see below). He will continue to cast Magic Wall followed by his ultimate spell until defeated.

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

Note for playing with the Duplicate Characters (dc) flag: unlike your player characters, whose abilities are determined by the form they take as opposed to their palette, Magus's ultimate ability is determined by who the game thinks he is, ie the palette. If you see Crono with Frog's palette, the ultimate attack will be Hexagon Mist and not Luminaire.