They often don’t kill sleeping monsters. They play quite smartly, but not at the same level as a person and they make many predictable choices… that’s all so you can beat them more easily and exploit some things.
If there’s anything stupid a specific monster is doing then point it out. The Devs are happy to fix some things which are obviously wrong.
That’s how I defeated the great captain of the Khanate. Arborgias couldn’t use SOLO, RAW or LINK Deathstroke, his only effective move was Kinslayer on Vegitiger.
And they got stunned for a long time. Enough to trigger death sentence and give Rattlesnake enough time to kill Arborgias and Nukespider.
I’ve been meaning to make a more in-depth topic about this for a while. I’ll keep on testing, but long story short, the AI is semi-random to prevent action loops and make it less easy to exploit. However, this sometimes leads to it doing something extremely stupid