"May the odds be ever in your favor" is called a catachresis, or a figure of speech that expresses something impossible as if it were real. You could also call the saying "absurd." Why? Because the "odds" is used to mean the probability of winning, and odds "in your favor" means you have the greatest probability of winning. Since the probabilities add up to 100%, it means may you have the biggest across you and your competitors. This can only hold true for one competitor - only one player or one team have the highest probability - that is the odds in their favor. So what the adults are saying to the kids is, essentially, you are probably going to die, but we want to you hope against hope that you win. The adults are, in a sense, making fun of the kids, who are too afraid to understand, and they are laughing behind their backs with this absurd wish. This bit of arrogance, along with the whole exercise of power in such an unjust way, marks those adults as extremely evil, regardless of whatever justification they are using.