Quote from pataterose;205565:
8 mage party, waiting at spawn points with r1 thunder/fireball ready
Fireball is too slow, I don't see how it could work seeing as how they're instant aggro and start off running.
Ice Spear can OHKO on level 6. I haven't tried on level 7, so I'm not sure if it still works there. I stand behind WM pet as a precaution since the range is shorter.
Either way, three mages is enough to clear assuming they can aim properly (a single TH user can hit all the center mobs). Additional members would just be backup/leeches.