If you watched the top eight of PT Austin last weekend, you may have noticed that game five of the Kibler-Papatsarouchas match in the quarterfinals seems to have swung on a missed Angel of Despair trigger. Josh Silvestri commented on that in his column this week, largely from the perspective of trying to prevent these kinds of situations. Following a fairly extensive debate over Brian's knowledge and intent in missing Papatsarouchas's trigger, Brian himself chimed in:
I knew that Van missed the Angel of Despair trigger. I held my Baneslayer Angel in my hand when he cast Hypergenesis because I didn’t want it to get destroyed by his angel. I did not, however, know that it was a mandatory effect and assumed that he was missing a “may” trigger, and I wasn’t about to ask to read the card or anything that would remind him to use it. It wasn’t until the reporter Josh Bennett asked after the game what the Angel had destroyed and we all looked at the card that we realized it was a mandatory trigger.
I certainly didn’t intentionally cheat, but I do feel bad that the match was decided the way it was. Given the circumstances, I’m not really sure how else I could have handled the situation, though - if I had looked closely at the Angel to be sure whether it was a mandatory trigger or not, and it was a may effect, I would have given my opponent information that he was missing the trigger and give away the game.
In other words, if you ask the GM about traps, he'll suddenly remember that there are supposed to be traps. Really, there's no other way to play this, as pretty much anything Brian did there other than "let the game flow normally" would have handed information to his opponent, and might have reminded him of an option he appeared to be forgetting he had.
While it's both players' responsibility to make sure the game follows the rules, it's clearly each individual player's responsibility to know how their cards work.