The worst part of the level is the first half. You don't see many Magus Demons (the ones that removes the shield) after that. As I said on the post, it is a super cheesy strat, as you do most of the damage only by reflecting it, I'm not proud of it :P but it seemed impossible for me to get 4*... not even dreaming of getting a good 5*.
Regarding the Magus Demons, this is where Soldier Eddie comes into play with his roullete, tons of power points. I had to cast the shield in almost every turn in most of those fights. Sentinel Allied Soldier does close to none damage, but has a lot of HP and the most important thing is his ability to remove debuffs. When you play with reflector shields the more HP you have, the more damage you'll tank. Remember that the shield reduces damage by 50%, so a 2k attack on a 13k or 15k character is not that much.
Let's say you tank 4 2k attacks, 8k/2=4k, you are doing (without even attacking) 2k damage to EVERY opponent EVERY round.
For those who say it's impossible, you are not leveling your talismans. Simple as that. Leveling Talismans opens a whole new game.