Ardyn has subjugated the pyreburner, Ifrit on my world. I know the Solheim fought with the Astrals as well. Though they lost in the end, it is certainly possible to war with the gods. It's simply a matter of knowledge. Anything can be defeated with enough knowledge.

For now, Ardyn was able to accomplish this task due to the many daemons he absorbed and his ability to control that power. In time, I will use magitek to be able to fight the gods as well.

[He was confident in that. He had no intention of being stopped.]

We've much to learn about the gods we're facing here, however.