According to Wizards of the Coast, the official MTG card sizes and dimensions for competitive play are 2.5 inches (6.3 cm) by 3.5 inches (8.8 cm)
If you give an opponents character the Reckless keyword and leave one or more of your characters exerted, your opponents character must challenge yours unless they can be otherwise exerted
Others have scanners that misidentify every other card
You also can't move backwards through the dungeon for extra buffs
9 Plains By Stephan Martiniere - $34 Magic Premiere Shop 2005 #287 (Japanese) This fantasy-style design from the Japanese Magic Premiere Shop series, distributed via selected game stores back in 2005, is sure to be recognizable to fans of Stephan Martiniere
While it's pretty unfortunate to draw this card early in the game, the potential payoff for playing Retether in conjunction with your commander is immense, and easily underestimated