Note that if you go too far, the ruin guard’s HP bar will reset.
Use elementally charged attacks. To use an elementally charged arrow attack, hold the bow button down until you see Pyro/Electro/Anemo coming from the end of the arrow. Release when the crosshair is pointed at the ruin guard’s eye. If the ruin guard is firing missiles, you can stop the missiles from firing by hitting the yellow crosshair for the brief three seconds before the missile launches. If you do this a second time before a shield forms around its core, then you will effectively disable the ruin guard.
You may want to use certain elemental burst attacks after the ruin guard is disabled. For example, Amber’s Fiery Rain attack and Lisa’s Lightning Rose attack are not super effective if the ruin guard is not disabled, as they may move out of the attack’s range.
Run away when you see the ruin guard reactivating. The guard can deal massive physical damage if you are in close range.
