On my initial flawed run-through I only saw Invisibility at Ellinia, so no luck there.
And while I could do a short trip to Demonis to pick up Lightning/Fire Rain/Ice Snake/Armaggedon I'm not a double-casting mage.
So it looks like the old tedious route for me, Inquisitors-Chargers-Resurrect, for my second run-through. I have Necro Call/Book of Evil/Phoenix as available decoys, but I'll try and see if I could do without these as the only summon spell worth its crystals is Phantom IMHO since it automatically scales with your leadership.
Nice screenshot of the enemy composition, but for me those bunch of Demonesses would cause fits for my Invisibility-less army.