[Saber Cherry]

Apologies if these are invalid, I don't know CB stats offhand. That said...

With only conjuration, you'd be toast. If you have Evocation up to Seeking Arrow, spam his mage-rich army with those, or hit his Capitol, castles, and grasslands with Hurricane.

It may be too late now, but you should have positioned Consorts in your neighbors' rich provinces to paralyze them.

If you can, hit him with trolls (poison immune, IIRC) and a Celestial Master communioning up to Foul Vapors. I think that's Water-Nature, right?

Make sure your Trolls are doing Earth Power -> Blade Wind...

Try Shadow Blast. Death 1 plus 2 Death Gems can cast it. It's even better, of course, with a +Pen amulet and Rune Smasher or Skull Staff, but you don't have what you don't have.

With a Phoenix as Tien Chi, I would have gone for Enchantment ASAP to get Flaming Arrows. Ah well.