Here's a really easy solution to the mind control. Right before you start p4, go run one character behind his statues in the room. This will line of sight that character and it won't get mind controled. Preferably something that can heal/tank the damage from kael and the rest of your team. When he hits the transition to P5, I like to run everyone but one character behind the statues, this way a freak mind control doesn't take you out.