I got him too in the festival. I haven’t evolved him yet because I don’t have a Crown, but his double dreamhunt is very powerful even in unevolved form. He essentially kills both monsters as long as one is asleep.
Much better than Banedragon, whose Double Poison Eater does much less damage to an unpoisoned monster even if one of the targets is poisoned.
I ultraevolved him. I use pull back as a way to summon two more rockoids. Additionally, I’ve used it to escape temporarily (if there is a sleep killer coming next or if it was poisoned and will get poison eaten.)
If you do the same thing to doomengine when he is sleeping but still shielded, he wakes up but suffers no damage. And I’m not sure the same thing would happen for a random monster who was in stealth mode.