Dash and bash baby!

I like the sound of that.

Anyway, here's the reason. Kostyan has a high number of kills, I'm guessing. Wait for the inner to start throwing out holy light and retribution. Go with a polearm, so you get less attacks which means less concealed attacks. Hope for the best, that your bashes work successfully, and eventually, the inner will get him. There aren't too many warriors who can solo that watcher, I'd say.