Creatures deal no damage this turn.
Simple enough, isn't it? If you haven't experimented with Fog and a creature based deck, I suggest you give it a try. In my experience, you will catch someone off guard once with Fog--after that it seems opponents base their every move around you having 3 more Fogs in your hand. Opponents tend not to ever attack with all of their creatures from that first Fogging on--too afraid that you'll catch them with their creatures all tapped and kill them with you own creatures. Fog has personally helped me win many a game. I can't remember how many times someone would attack with every creature they have in play (undoubtably bigger and better creatures than mine) only for me to Fog them all and retaliate with a counter attack of all of my creatures the following turn (assuming my opponent ins't playing green). Make sure to always use Fog as late as you possibly can--if you foolishly Fog before attackers are announced, usually your opponent won't attack with anything. I hate to admit it, but I have even used Fog to cover up attacking errors I have made. If I see an opponents chooses to block my creatures in an undesirable way, I have been known to Fog my own attack. Fog can also be used with: