Thanks for the criticism and consideration, I'll be including some of your thoughts the next time I update Urdheim.
Well, the Firebrands are quite good offensively for their cost, but they are far more fragile (with about 1/4 of the hitpoints of salamanders and 1/3 of the prot), not only in dying to archers or spells, but also able to miss with their attacks and kill each other and your other troops off. However, you're not the first person to mention raising their cost, and I'll likely be doing that in the next version.
I liked the traps too, I think it was the most fun/creative part of Urdheim.
So you didn't find the 300 non-sacred gold cost of the summoners prohibitive at all? So with the upkeep and the basecost, you've spent 540 gold to get 11 wyverns after one year. Obviously as time move forward, they become a better and better deal, but to get the most out of it you need to buy a bunch of them, and that means you're not getting mages, which means you fall behind the research curve. Though I'm hesitant to raise their price, I'll give it some more thought and consider some other tweaks, especially since you're not the first to mention this.
Base kobolds are
_5 hp
_6 str
11 att
11 def
_4 prot
_9 mor
12 mr
The med infantry essentially have +1 to stats over that, and are double the cost. Kobolds tend to have higher att and def to their speed, quick reflexes, and very skittish nature.
I think I'll be raising the resourcecost of the Med. Inf. by one and consider changing their name or at least expanding their description.
I think I'll lower the siegebonus by 2, and lower their cost by 2, (a drop in effectiveness by 37% and a drop in cost by 17%) which means you'll need a lot more of them to get things done.
I'll be examining and playing through Urdheim more thoroughly again, and revising some costs / stats. Even a modest 10-15 changes, can have a more significant impact on how the whole nation plays and how effective it is.