Flame lurker can be beaten quite easily by a mage with the right gear. Equip thief ring, the most powerful bow and toad eye arrows. Simply pick him off from a distance, roll away and repeat. Alternatively you can give him the runaround and trap him behind some of the bones then just pick him off, not as much fun but it does the job. Taking him on toe to toe as a mage is virtually impossible unless you have the PFS +10 (with str to carry it) + ring of flame resistance. Melee for me was fully powered up mage, no shield, using high powered soul arrow then dodging as appropriate, he is highly allergic to magic, wasted him many times this way :o)
Mephistopheles was right about you……………