Blink specifically states that it will cause 5 damage per round to a champion that is sitting on the spot where a champion is blinked. I think because of the IS bonus of -6 spell damage, it is actually causing 0 damage. I'm sure that this was changed in the old client, so that even an IS champion would take the 5 damage. It seems under this new client, so many of the old bugs that were fixed, now reappear.
My opponent moved all around, but I can't tell you specifically what squares he was on. If you're online, we can test it when you have a chance.
I wont be online for several hours. Reason I ask though is that the top space of a 2x2 champion is the space used for targeting for knockback, pull etc.