The scenario is essentially that crawlers deal low damage without pack mentality and they're trying to kill a tank, something that even in SW3 they often have moderate difficulty in killing. And since Deads are Chaos' main ground range unit they're gonna have some difficulty killing it
I was thinking in CvCai match was… you could have save your Bombers later when those pesky Deads came out (you can also use to scary them away because the AI always falls back the bigger army you had), then send your Crawlers to the Brainrotted Guy followed by these Little Tiny Furry Ones, and finally charge your suicidal maniacs to the Cats and Zombies for a massacre. In alternative way: you should go harass their base, so you could also kill their miners too (don't forget the cats) because that's when you're freak out of how fast reinforcements the AI had few seconds later if left untouched.
tip: play on grass isle it pretty much help u a lot with the ded also u should play normal and buy jug instead range unit and then go eclipser after that it up to ur game skill I beat it in 13 mins