Great idea for cheap adversaries!
I have quite a bit of these 1/72 Dark Alliance figures. Heads-up...these Anubis warriors are taller than most of the others in the line, so even if they blend ok with your 25-28mm some of the others might be too small.
You have the trolls and cyclops, I think the Minotaurs might be compatible with your Oathmark, but not as imposing minotaurs, but more like another group of "beastmen" to go with these dog-headed warriors.