I've had the anchor guardian leave its spot and attack local dremers. Love the help but it seems strange.
A little nitpick. I believe the Demonwood is actually not a Dremer unit, rather it guards the Anchor.
Same with the Cockroaches from Hell (and others besides)
Also Im learning to appreciate the Archers of Helia for their range 3
It's easy to get carried away with "nah, I don't need ancient ruins, I need gold" kind of thinking.
On the other had, cheap way to get some research for humans is to build mana trap and then library in several cities.