Chain CDs and kill them before they kill you, nothing more to it really. You can stun them with remorseless winter, giving you a few extra seconds. Tbh I thought the first boss was way easier than the trashpacks before.You're gonna have a bad time on the second boss with your gear btw. unless you use Mione cheese strat. And the third one is probably pretty much impossible. If I was you I'd head to Iron Docks after killing the first boss in Auch, maybe Shadowmoon.