here is how i did 338%: 4 rogues; skills: hide, sneak attack, rest into poison craft; stats into strength and endurance for 3 melee rogues, dex and endurance for 1 ranged rogue; use hide a lot pretty much and you're done
My attempt for maximum damage using biological(withdrawal combo) and also maintaining 3/3 crystallize ability. Used corrupter as test opponent: Lvl 30, stat points all into speed, velocious set with flame katana(katana gives highest speed in game), abilities to note: 4/4 corrosion, 4/4 withdrawal, 3/3 crystallize, 1/1 toxicant form, 2/4 integrity, 3/4 savagry, 3/3 agile exposure, 4/4 shadow blend, 3/3 evolution, moveset in order of use: crystallize, corrosion, toxicant form, shadow blend, agile exposure, withdrawal, critical hit of 43151 damage, cool