Newbie questions about SuperCombatants

[MagicDinosaur765]

Thank you another time. : D

It will be an Arch devil with Fire-immune good troops, so I thought in Fireball or Fire cloud (both don't need a lot of research).
Falling fires? Wow, I thought it was a bad spell. Is it good?

The troops would stop attackers, so maybe I don't need two shields. Is it?
And I was thinking in Phoenix pyre, but it is an Alteration 7 spell (too much research), so it will take a lot of time.



So, do I use falling fires? It is really so good?
Do I use two shields if at least 10 good units (devils and the earth-blood horsemen) will protet the Arch devil?



Thank you very much, really ^^