Prowling Shades, disappearing even when effected by example by freeze

Well, personally I found this type of monster the most annoying one so far.
They can disappear and just appear somewhere else, but they can do this, even when affected by things like freeze/stun.

The biggest problem with this is, if they are a RARE monster, that has life regenerating or helps allies.
I had several maps, that I could close, because due to combination of being rare and prowling shade, they were just unkillable.