its really hard to do world quest,i have 577 ilv and still cant solo the harvester with 12m hp…i need to burn all my cd just to kill one of them,and i still need to kill bunch of them… 
Harvester? I’m assuming this is in Hallowfall I torch 4-5 of them with CDs but won’t pull a second one before the 1st is below 30% hp without CDs.
That being said I do spend a lot of time below 40% HP.