Tips: How to beat the second "Double" (SPOILER)

[PHJF]

Yeah I figure I will be able to win that easily if i take like peasants in.

Soul Drain is currently 40% at 45 rage with a cooldown of 1 turn. I have ~70 rage if I use a demonic helmet I have, so right there in two turns I can take down 40% of two squads with just Spirits alone.

4300 damage ice snake or 3200 AoE fire rain will twice per first three turns will help as well 110 mana is a lot to burn.