I'm sure people are getting sick of me posting errors, so this is probably the last one for today :)
Anyway, this is one you just probably haven't updated since X and Y came out. Defog now clears away Light Screen, Reflect, Safeguard, Mist, Spikes, Toxic Spikes, Stealth Rock, and Sticky Web from both sides of the field.
The stuff in bold is what is now different. Sticky Web was introduced, so that is affected, but more importantly defog gets rid of the mentioned affects from your side of the field as well as your opponent's.