Because a huge majority of Magic tournaments offer prizes to earn in addition to glory and because it can happen that a match result is detrimental to both players, two players can be tempted to agree on a specific match result so that at least one of them ends up in a more favorable position standings-wise. There are circumstances in which agreeing on a match result is perfectly legal, but very often players put the feet on a slippery slope. What's ok? What's not? Where's the line? What should