Sounds like you need -enemy Fire resistances. Use "Rha" Runes in your sockets after your resistances are maxed out. You want to try and reach around -100 to be most effective in the areas you're farming (K3K, Tran, etc.)
Well my resistances are 83% fire and 80% the rest and i have pretty decent -enemy fire resistances now. 124 lvl, around 200% mf (and merc around 80%) but gosh... drops are so poor. Cleansing full K3K sometimes doesn't give me any TU/SU/Set. Dont have any good items yet, cant make 120 lvl rifts and ubers. Tried Teganze but though 7500hp and 80-83% res i am dying within 3-4 shots. Also my dmg from Flamefront is around 4k, and 6k from Flamestrike but literally i need a lot of shots to tear them apart. I finished Duncraig and killed Assur but it took me like 2 hours and around 15 deaths.
Merc is totally useless in 120 lvl rifts, he has got good gear but dying instantly in Teganze or Duncraig. I feel like season will end and i wont find any decent gear and make any 120 lvl ubers. Rotfl.
Idk what i am doing wrong. I remember when i had ele druid on patch 1.7 and it was so easy (Hurricane killing everyone in 2-3 seconds), cleansing Teganze and Duncraig in 30min at lvl 124-125. But this sorc is kind of crap, but maybe its a gear... since i cant find any decent items and drops are so poor though 200% mf (280 with merc). Merc is doing fine in K3K and kills a lot but still nothing drops, only yellow crap items. The best items (but still average, comparing to what people have) i've got from Goblins.
Btw didn't meet a single Rainbow Goblin yet
Staff of Herding is totally useless for me.
I still love the mod, it's great and fun but drops are rly so poor in TSW. If no Goblins (especially Rift ones), i would still play with TU only, lol.