So the victim's heart stops beating for the duration of the next round? In that case, I would think that the victim's turn would be skipped. But it doesn't say that the victim can't attack or heal, only that she can't defend. If their heart is stopped, I would think that they wouldn't be able to do anything at all.
Also, if I use this on someone, would I get a free attack on them right away, or would I need to wait until my next turn?
"Beginning and ending on the turn of the player of this card." There are several cards that say this, Heart Breaker, Time Out, Manhandle, Thunder Head, etc... But does that mean the beginning of that person's turn, or the end of their turn. If I used Time Out on someone, making them out of the game for 2 rounds, after the 2 rounds when it is my turn, would I be able to attack them, or would I have to wait until my turn came around again? If I used Thunder Head on someone, making their attacks -1 for two rounds, and it was my turn at the end of those two rounds, and I attacked them, but they Blocked, Grabbed, and Smited me, would their Smite be worth 6 or 7? If I play Heart Breaker on someone, making them unable to defend for 1 round, when it is my turn again, ending the round, are they still unable to defend against my attacks?