Bah, I'm playing a game as the Shieam and I didn't build any pyre zombies because I never saw a mention of their exploding thing. They looked just like axmen without the bonus vs. melee so they seemed like a waste to me. This game really, really needs to be documented better.
But without the pyre zombies and without the eater of dreams (when do those appear? what do they do?) I am kicking all sorts of ass with the Shieam. That trait combination is simply deadly. Once I got conjuring I went on the war path and destroyed my neighbor in like 4 turns.
Half a dozen conjurers is all you really need to take down a whole civ. That is the power of the Shieam. Just make a few adepts early in the game, and that is all you really need. Spend the rest of your time building up your civ and let the handful of mages & conjurers destroy the world. Almost too easy. Haven't even gotten to summoners yet, but the game will be a joke by then.