When casting Doppelgang w/ X = to 10, one of my copy targets was Waterknot. There were only 5 creatures on my opponent's side, and 3 on mine. I was unable to resolve it bc I had no way to put multiples on the opponent's creatures, and even though I even tried choosing my 3 creatures, I couldn't get to the 10 it wanted me to select. Trying to select a single creature to get multiple copies merely unselected it as a target.

Log Attached.