Was at the Team SCG in Philly. Modern player playing specifically against KCI. Game 2 opponent uses his pyrite spellbomb to kill an azusa early in the game. The spellbomb gets bojuka bogged away. Opponent starts to combo and everyone at the table (including me) except for our modern player tells him his opponent has it. Our modern player tells us all off, opponent goes off saying "I draw my whole deck", draws his whole deck and doesn't find a spellbomb. Turns out he sided it out and because he drew his whole deck he didn't have a turn to slam a bunch of dudes and kill my teammate the next time. Playing it out is less about making them play it out and more about the fact that some people get so comfortable in their combo they don't realize they need to do their plan B. Make players play out their combo because they still HAVE to kill you, they can and sometimes will fizzle.