I just finished the level 20 summoner avatar battles, and wanted to share my experience. To a veteran linkshell like ClanAM, this certainly isn't new, and perhaps seemingly obvious to many, but this is my take, and education by trial and error, on the goal of obtaining avatars.

I tried to study up a bit before the battles, and found two basic strategies:
1) The Two Searing light method. Cast Carbie, run-Carbie is defeated, recast Carbie, run - Carbie is defeated, recast etc..then Searing light.
2) The Three Searing Light Method.

As far as method 1, that was what I initially tried, but found eventually the Avatar caught up to you, and things got a bit tense. Casting interruption, and surviving with potions was a loosing battle. So, method 2 is what worked best for me, so that is what I'll discuss.

Any good place for a party of level 64 to earn experience in Aht Urhgan?