PoS = Pissorf Spam. For full synergy go Orc with Crystal Ball, say Wizard, and prep Binlor for Pissorf. Swap into whatever refills you. Use leftover resources to take on Avatar.
Remove some walls with Binlor to open up the Secret Sub and for ease with moving the djins, move the one in the top right next to the one in middle tiright, the same with ones on the left, and finish off the southern one with fireballs once killing the other ones has leveled you up. (You can start the fight at lvl 4 comfortably amd just pissorff the djinns into each other minding not to slap the one with Phy into something but the other guy into him). Then just deal with the avatar with what you have left. I ussually start the fight at lvl1, and if you have wheytwut you can just move all the djinns to one spot and PoS them all down easily.
Any ding happy Orc should be able to do it for sure, Fighter, Assassin, Sorcerer, Thief, Rogue whatever. You don't have to be an Orc, they are just the most straightforward. I'm only missing the rat and the assassin there on this playthrough and most of the wins there were done that way with various things.