When encountered the first three times it is indestructible, and the player must flee or have their party killed. The player can first encounter the Guardian if they attempt to enter the Imperial Palace on their first visit to Vector. After destroying the Magitek Research Facility, a Guardian prevents the party from entering the city. Three Guardians accompany Kefka to Thamasa and prevent the player from leaving the village while controlling General Leo. In Kefka's Tower, the Guardian reappears as the final boss before the player meets the Warring Triad at the tower's summit, but this time it is now vulnerable to damage.
The Guardian can be a difficult boss. It runs several "Battle Programs" which allow it to mimic former bosses from the World of Balance. Between each program, it resets to its weak default mode. Its Programs run in this order: Ultros, Dadaluma, Air Force, Ultima Weapon. Dadaluma's program can be dangerous because it throws weapons at the party for unblockable damage ignoring Defense. Ultima Weapon's program is also dangerous because it uses Flare Star and Mind Blast. Guardian is weak to Lightning, which is an easy weakness to exploit with Thundaga. It can also use the Wave Cannon after finishing its countdown. If Locke is in the party, he can steal a valuable Force Armor, which is an armor that comes in limited quantities.