(spoilers)

I'm most of the way thru my evil campaign, where I intend to kill all the other masters.

I killed them in the order of who hated me the most.

All that's left are: key master, devil, dragon, the engineer.

I was going to kill the engineer next, but he's got his shield up. I was hoping my gremlin would help with that, but no luck so far. I've got a ton of turns left I think, and there are still unclaimed neutral shards. This is Genesis.

Am I ever going to be able to invade the engineer's shard?

(edit) Well, I didn't need to do anything. I never had an option to talk to Zarr about the engineer, but a few turns after the first time I attempted the invasion, Zarr told me the engineer had been captured by the underworld, and his shard is gone.