How to Easily Defeat Agnus Boss (Vergil Only) | DMC4

First of all, make sure your that your DT and focus gauges are full (by fighting regular enemies before entering boss room). Now all you need to do is gather all the flying sword enemies at the window. Activate your DT and strike them like there's no tomorrow. Hitting them during devil form ALWAYS makes them impale the window! (if they're close to it) Lvl 3 focus gives additional propereties to your yamato sword (it multiplies your attacks) so you can score massive amounts of damage in a very short time.