I messed up one JFJC and it ruined my perfect fight against the first army of Frost.. My timing was a bit off for most of this Mission. I'm usually a lot better at using it. This is probably one of the hardest Missions on LDK for Vergil, but the part where your stuck in a long hallway with dozens of Frost spawning is one of the toughest parts for every character.. You'll definitely want to use DT and JCE immediately if your going to use it because they start spamming projectiles as soon as they spawn and have ridiculous range. You can use DT Rapid Slashes to approach and before using JCE. The best method for dealing with them is definitely JFJC and Rapid Slash. Sometimes you can launch them with Aerial Rave B but it's a bit unreliable, you can also stunlock them with Yamato Combo C or Force Edge Combo B but the earlier hits don't stagger them so they can hit before the rapid attack.. If you get them on their own just spamming JFJC or launching them into a charged Beowulf dispatches them easily. You can break their shields in a few hits with JFJC at max Concentration, Vergil mostly struggles against them when he has no concentration and it can be difficult to build it up against them.