So, what can be done here?

Even though a lot of time has passed, I think you should attack first. Level up your Summoning skill. No need to comment on that. On the first turn, you'll summon everyone, including Devils. And you'll have an army that's not much smaller, and considering the initiative, there's a good chance you won't lose. Use dark magic and Temptresses. Cerberuses, which, with a successful attack, can capture 3-4 stacks of the enemy. And Mass - Dispel, Berserk, and whatever else is available. The strength of the Demon army isn't in the number of troops at the start of the attack, but in the number after summoning them from the Abyss!!!!!!!