Boons in high level fractals
I haven’t run any high level FotM yet (currently up to difficulty 9), so I’m just speculating. But if there’s a lot of Protection on the mobs, sounds like the answer is specifically to bring a Mesmer or Necromancer:
http://wiki.guildwars2.com/wiki/Boon#Skills_that_remove_boons
Failing that, some traits (e.g. Guardian’s Searing Flames) will remove boons too. Otherwise I guess dps through it if the situation permits. :S