Having played a lot of games, I can say that, while Mage Wars takes a new slant on many things, and brings several things together in one game, it does not, mechanically, represent anything "new" to the world of competitive gaming. There is precedent existing for other games that can easily be adapted to Mage Wars.
In the example of "must reveal" enchantments I would apply the golden rule, which is that each player is his or her own opponent's keeper.
In the case of Must Reveal enchantments:
As a player, I am responsible for ensuring that my opponent is not cheating (intentional or unintentional...doesn't matter either way) in the matters of activation tokens, spell choices, mana use and management, life tracking, etc. The burden of responsibility is on me to keep an eye on things, and make sure the game stays kosher.
In the Game of Thrones LCG, published by Fantasy Flight, at major events there is one judge per long table. For reference, a "long table" hosts approximately 15-20 games, or 30-50 players. A parallel mechanic would be that "In Shadows" mechanic. In GoT, certain cards can be (must be, whatever) played "in shadows." It is an illegal play to put a card without the Shadows mechanic into Shadows as there are many cards that specifically interact with cards that are In Shadows. At any point a player can request the judge to confirm the cards his or her opponent has in shadows. Judge comes over, takes a quick glance, nods, and moves along.
Here's the thing: Even with only a single judge per long table, there is no lack of a judge when you need one. Judging competitive events, at a high level, should be done quickly, mercilessly, and professionally. The average question should not take more than 5 seconds of a judge's time. That allows the "un-average" question to take more. It allows judges to be more free with their positioning.
What is all this in aid of?
Well, simple. As my opponent's keeper, if I take issue with a play, or suspect deliberate cheating, I call over a judge. That judge probably isn't able to do anything at that moment. As has been discussed, the must-reveal enchantments will be hard to weigh on, because it's player A vs. player B, and neither is going to capitulate fault on his or her part. So what's a judge to do? Simple. The judge keeps an eye on things. It happens all the time. It's not an unreasonable expectation for a judge, alerted to a possible cheat, to pay special attention to that person's games. Active judging takes hold, and if the judge catches a cheat, then it's a DQ. No questions asked.
Alternatively:
Active Bystander judging is another option, or an option to be applied in tandem with the former. Active Bystander Judging is implemented by Wizards of the Coast in all Magic: the Gathering events. Players not actively participating in a game are encouraged, required even (as per the official tournament doctrines of WotC), to "speak up" in the event of anything amiss. Mob Mentality rules on this side of the coin. If 5 people see that there was a duplicated enchantment, and only 1 dissents from the opinion, it's pretty clear which way to rule.
Bottom line:
People are going to cheat in any game where they feel the reward outweighs the risk.
People are going to cheat in any game where they feel they can get away with doing so simply for the sake of winning.
That combination = PEOPLE CHEAT. You can't build rules around it. The more rules that stack up the more people are going to try and beat them. You can't account for everything. The simplest, most effective deterrents to cheating is to enforce strict penalties for the action, because the more strict the penalties, the greater the chance that the first category of cheaters (the ones who cheat because they feel reward > risk) will shrink.
I'll elaborate:
If you tell people that persons caught duping enchantments* will receive a warning, a second warning, and then a disqualification, well, you're basically inviting people to cheat until they are caught twice, and then stop cheating.
If, however, you tell people that persons caught duping enchantments* will be disqualified, and banned from future sanctioned events for a period of 4 months, then you are encouraging them very strongly to not cheat in the first place.
* a judge rules that enchantments were duped
-nihil