I was blasting my way through a pack size challenge map, and had the usual few ghosts popping up, when I witnessed a new kind of ghost. it was a teleporting ghost. I think one of the map affixes was +1 affixes, so I wonder if a teleporting monster became a teleporting ghost. thankfully, it didn't attack me, just followed me around. I was able to teleport away faster than it could keep up, so it didn't mess up my ability to finish the map. I don't know if this was part of the reason it was teleporting, but it looked like it had died from a shock attack.