Deranged Brute

If you are leaning into the rage archetype, Deranged Brute is an obvious pick. It means that every stack of rage is now providing five damage instead of two, more than doubling its effectiveness. When paired with fledgling imp, you can quickly create a very high damage floor. I would prioritise defensive upgrades to bolster its middling health, as if it is doing its job correctly you will have all the damage you need so long as he stays alive. Obviously, the rage upgrade can work wonders for setting up some fast damage at the start of each combat, though it doesn't necessarily have to go on this unit.