I know they said they would nerf zFinn but a "hey guys we are nerfing him today" post would be cool. Either he was nerfed or I had some wonky RNG tonight. I went from a 100% p3 clear to running into...
Bad RNG as others have said...also, were you keeping Poe buffed? Foresight doesn't count against the canon. You should make sure Finn or BB-8 buffs him right before the canon goes off.
Also, having R2 stealth everyone will help stop counters on the boss.