It was designed to be tricky - but there are definitely ways to beat it, swarm or unholy tomb are great options
You have to go really slow, they won't invade you. Go font by font. I used SP earth shakers on the lt and just stealthed away the weaker guy( to avoid losing to withering fern which i did twice). That's pretty much it. I did nothing fancy but use imune physical and use detection unit (head shrinker). toke me 3.5-4 hours to beat them i'de say though. Oh and havocs touch+ zealtry made the LT god. A fast way to win I realsed the last try was to use skull totems and punishing aura, stacked them for like 45 loss of life dmg. The Ai won't move or do anything aginst immunity physical.
I haven't yet, but I plan on cheesing my way through it after I buy it tonight. I'll probably use SL.
heretic overlord, I have no idea why I thought his name was deep elf lieutenant. Btw you won't be prepared for the ending, but i want you to suffer like I did so deal with it.