The level I'm on has a huge split in the middle, and I need to claim land near the enemy so I can move my monsters there to start attacking (I can't research ANYTHING in this level for some reason, so I don't have Call to Arms available). From what I've read, you are supposed to be able to claim land while possessing an imp, but as the game tells you nothing about the possession controls, I can't figure out how to do it.

What map? What kind of split it is? To claim land when in possession mode, step on a tile next to one you've already claimed, then use your primary ability, "dig", by clicking the left mouse. You can only claim unclaimed dirt floor that way, it doesn't work on claimed floor, even neutral one.

I think the map is Snuggle Dell. I didn't know the unclaimed land had to be connected to something I already own. The level has a big pool of water in between the two dungeons, so I can't just make a steady progression of land-claiming. I already had them clear out the giant gold deposit around the torture room in the center, but they didn't claim any of that land either.

Well, after restarting, it turns out it was a glitch. I'm able to research now.