Would you care to elaborate jhaelen?
Isn't that obvious? If you cannot play the game without making (rule) mistakes, there must be something wrong with the game('s rules).
Now, don't get me wrong, I enjoy playing games with complex rules, e.g. Arkham Horror, which has an insane amount of corner-cases and non-obvious card interactions, once you play with all expansions. Or the Call of Cthulhu LCG which cannot be played without an intricate knowledge of the game's current FAQ.
To be honest, if I got to play Mage Wars as often as either of these games, I would probably make less mistakes, too, but I still think it's harder to miss them as in either of the other games. First, Mage Wars has an ever-increasing number of keywords, many of which are similar. While the Codex helps, definitions too often refer to other entries to grasp all of the implications. In Mage Wars, cards also tend to have a lot more text than either of the mentioned games.
And what seems to trip up even Mage Wars pro players: the game board is too busy. Between stacks of cards distributed across and around the board and various counters it's just too easy to miss something.