This is a bug
Well, this is about a roshan-morphling bug.
When you are using morphling, go to the secret shop, then go to the farthest bottom right side of the shop. You need a courier to see roshan. If your courier sees roshan, use waveform between roshan's feet. And then, TADA! You can now attack roshan without you being attacked
-note, after the waveform, you need to put out your courier so that roshan wont move and if you have your allies with you, roshan will move and you are already out of the bug!