I had something of a similar experience when playing co-op with a friend.
We were trying to break down a door with Boulder Dash, and he discovered that he could jump past the door with Phoenix Dive. As he jumped, my boulder got through the door, and he disappeared into the distance.
It seems that targeting his ability where my spell would end up causes this to happen. The bug worked as long as he targeted any part of the trajectory of my spell, but the timing is a bit hard to get. We could replicate the bug with a little effort.
Sadly I can't get video of it, but I have a screenshot of where we ended up when we first discovered it. We actually ended up outside of the map, in the blackness, just below this point. He jumped up here with Phoenix Dive, and I teleported after.http://s29.postimg.org/z4ez3meif/2014_02_12_00001.jpghttp://s12.postimg.org/qcz09dh71/2014_02_12_00002.jpg
edit: spelling, clarification