I went 40 arc and 21 fire , all 3 mages are all are scourch fire build. start out with all sourch (3x on traget assuming no resists) then one more round of scourch (now 5x on traget) 3rd round hit it again for crit burn then fire blast. most are dead then. for healers hit 2 scouch then POM bomb , blast , wave dead