xiAo-Shin Star I agree with you that Zown's idea sounds good but giving up 2 retals seems like too big of a risk for an undead player.
What I can say to you point about Skeletal Legion compared to Human infantry, because gnome infantry is much weaker, is that while you are correct that a 1 to 1 Skeletal Legion to Infantry, the infantry will kill 5 skeletons, and it take 3 skeletons to kill 1 infantry, Infantry train at 1/30 the speed.
So in the time it takes to make 1 infantry, you can make 30 Skeletal Legion. You outpace the humans in production, and that wins in 1v1 fights.
The problem I tend to have with fodder units is that it's unsustainable to keep building that much armory. You may have noticed the same issue, or perhaps that's not been an issue for you.
What I have seen is that Undead has some pretty strong units. You Knights are slightly better than Human Knights in my opinion since they cost a little less but have the same stats. How do the other units feel to you guys?