I used the strat to do everything but the last boss (I wiped x2) at lvl 23-24 with my team. The last boss is pretty tough at this level, but other than the Gatekeeper and Gregori, some of the wandering mobs seem tougher than the bosses lol.

Gregori is definitely an endurance test. What I do is have everyone assist until the three adds spawn, then I sic my bards on the spawns one at a time (I get them started, then turn off FTL Assist, and retarget Gregori), while I continue to beat down Gregori with the tank.

It's a bit clunky given that I have to target the spawn, play cadence, click my "Don't assist" button, retarget, etc., but it's pretty easy to suceed this way. I do need a way to turn the cleric off completely -- right now I have heal and dps settings -- the heal is on the same key as cadence, and in dps mode, she has things to do when the tank hits. I want her to shut up, stand still, and regen or conserve mana hehe. Even so, I command her to drink a mana pot mid fight and she ends the fight with < 100 mana, but we live