it was realy realy hard
Septimus needs alot of critdamge and setup.
After dismanteling several chars I could get him to 338% Critdmg.
Bad el is there for a 20%dmg boost with his poison passiv and the 2 Gurptuks for another 30%dmg boost (4 Poisons) Ruella brings the DEF Down and Weaken. Bad el must go befor Gurptuk. Speeds are not crazzy - all above 150.
After that the hit from septimus have to trigger Helmsmasher (50% Chance) and the spider is dead.