I went through the npc quest Mirror Images today as Blue Mage and thought the job performed exceedingly well (having also given this a shot on blm when my npc was 40, I failed miserabley). The big debate for me pre fight was whether to go /nin and tank Vassago, or to go /whm and have my NPC tank him (as PLD). The latter strategy won out and I ended up winning fairly easily. I had a great time with this fight because I felt I could be very versatile and enjoy the fight the way I wanted to.