[Boron]

Ryleh is an awesome nation.
The Starspawns are probably the best combat mages that you can recruit.
It depends a bit on the mods but if you play Vanilla additionally to your good mages you can field golems.

Just give your Starspawns Spellfoci and if you can afford also Runesmashers. Field a Staff of Storms.
Your F-Starspawns cast Astral fires, your "normal ones" soul slay or enslave mind.
With Spell Foci the Astral fires destroy troops very quick and your Soul Slay Starspawns normally kill any enemy SCs or even better steal them.

If you can organize the Chalice or GoH for you then you can cheaply do Mind Hunt without any danger.

Your armies are very mobile, you can teleport them in everywhere.
If your enemy has Astral-SCs you can sacrifice a few Starspawns to mind duel them.

Then you can summon Abominations as Routblockers and thus completely avoid using other troops at all, so you can spend all your gold on mages.

Coatls fit well in your armies too, they can teleport around with your armies and cast relief.

Ryleh is excellent since it is one of the few nations that can attack everywhere.