Magnetic Aura (2-MULT)
From Guild Wars 2 Wiki
Magnetic Aura is an aura that reflects incoming projectiles. It is applied by 2-MULT during a guild bounty each time 25% of his health is removed. Unlike auras applied to players, it has an indefinite duration and will only be removed when his stacks of Overload are removed. Overload can be removed by defeating and throwing unstable sparks at him which cannot be reflected.“
Reflect projectiles with magnetic energy.
— In-game description