If you have already a 4 creature on lane and play one instead of creature with last gasp- it will trigger last gasp. It is so stupid , easiest way to trigger last gasp- , Direwolf should fix it , creature should just dissapear if you replace it or players shouldnt have options to replace creatures on board. Or all 8 creatures in shackles , and opponent just replace one of it with creature that make other immune for shackles or playing creature with charge. Or for example if you silence creature to 0 attack or reduce it attack to 0 , your opponent just can remove it from the board . it s like give creatures with last gasp an "ON" button.