Just got rolled by AI Neifel. What did I do wrong?

[Sandman]

My national dwarf mages I had research as well, but every three turns or so, due to a huge death gem income, I had them summon up an army led by a bane lord of ghosts, pale riders, behemoths, and that one shadow skull-head dog ethereal summon.

If you've got a huge death gem income, forge loads of skull mentors and your research problems will be over. Heck, you could even go for owl quills as well.