[Nagot Gick Fel]

Others have answered the essential points. I'll add just one more tip:

It may not seem obvious, but don't neglect Blood Magic with Ulm. Empower a Smith in blood (up to blood 3). Forge Blood Stones and give them to your support mages so they can cast (with Earth Boots and Summon Earthpower) level 5 battle spells like Weapons of Sharpness (these mages can also Petrify/paralyze things with ease).

Don't lose time binding Demon Knights or Devils with that mage, though Hordes from Hell may be OK. Otherwise have him do what he's best for: a Lifelong Protections for 10 slaves, or a Soul Contract for 40 (pays for itself in 6 turns) are quite a bargain. And if you want that Father Illearth, it's unlikely someone will beat you to it - your competitors will rather race for Ice Devils.