Stuck in chapter 2 mission 1 boss battle

[Peterhausen]

As per title. I manage to reach Azuleir without any serious damage. And the boss battle plays normally, but then the Red Support Lance casts Flame Shower and it wipes out my entire team.
I put Satsuki on support with Ice Banish, it still has 12 uses left. She even makes sign of casting it when Flame Shower is used, but it's still casted and destroys my entire team in one hit.

I tried different formations, but they don't seem to be the issue. It's the AI casting Flame Shower in the first 5 turns and wiping everyone out.

[Last_Sinner]

From memory, there is a higher level of Ice Banish you get offered for Satsuki during 2-1. You need to take it in order to counter the Flame Shower. Also try to clear that mission in less than 414 in order to get the SS reward and get a stronger move. Groups of Nozomu/Nozomi/Green going North and Katima/Satsuki/Red going West are standard for Normal.