Resistance

Resistance is a battle statistic that determines how much damage an Adept or enemy takes from element-based attacks. An Adept will have the most resistance to their innate element, and have the least resistance (in most cases) to the element that is symbiotic with their element, surprisingly enough. For example, Isaac, an Earth Adept, will take little damage from Venus Psynergy used against him, but will be more susceptible to Mars Psynergy, as Mars and Venus are symbiotic.

There are three ways that resistance can be altered in Golden Sun: through Battle Psynergy such as Ward; with equipment imbued with elemental resistance, such as Storm Gear; or by setting different Djinn to obtain different elemental powers.

A full list of equipment which affects resistance to each of the four elements can be found here: Mars, Venus, Mercury, and Jupiter.