So during someone else's turn he played an Untimely Death, and so I played A Second Chance as a response (this is still during his turn). He then proceeded to play Smoke & Mirrors as a response (still on his turn) to cancel my Second Chance. I argued that you can't play a response on your own turn, and that this wasn't the kind of game to encourage that much effect stacking (counters on counters on counters, etc.). He (an avid Magic: The Gathering player) argued that of course you can counter a counter.
So, the question is, can you play a response on your own turn in response to someone else's response? Or, more specifically, can you play Smoke & Mirrors (on your own turn) when someone plays A Second Chance as a response to your play?
Sincerely,
Two Very Salty Roommates 
