During the quest “Blackout” in Grizzly Hills, you get to operate an iron golem mech similar to the war tank exploit that was recently fixed. This allows you to run around the area and two-shot mobs with your main ability with a 5sec CD. It isn’t very efficient, but the mobs give a normal amount of xp and drop loot even in the mech suit. This could possibly be automated since the mech has an infinite duration.