Toxic Avenger Ur-Sek

Stink Bomb ensures that every other attack is going to poison an enemy, then, those poisoned enemies starts dropping healing orbs through Hemotoxin, giving you massive sustain while Corrosive Bile destroys everyone's damage reduction, which comes in extra handy as you climb higher in the abyss and elites with massive damage mitigation starts spawning en masse. Also, secondary attack doubles as a long distance attack and emergency healing. This requires absolutely no catalysts to clear easily Abyss lvl 100. I could have gone way over that bar but the time it takes to do so at the moment made the point moot as it cleared everything needed to farm tons of catalysts.