Frostbite

Frostbite is a Frost mage PvP talent that gives your chill effects a 15% chance to also freeze your target for 4 seconds. Mage spells that have chill components include Frostbolt and Cone of Cold.

Tips and tricks
In PvP situations Frostbite is effective at catching runners or slowing large groups, which is invaluable in battlegrounds such as Warsong Gulch.

The Frostbite effect does not overwrite the Frost Nova effect or the Water Elemental's Freeze effect. These spells have a longer duration (8 seconds vs. 4 seconds) than Frostbite, and thus supersede it. Even if the Frost Nova or Freeze has fewer than 4 seconds remaining, Frostbite will not take effect. However, if the attack with a chill happens to break the freezing effect, it is possible for the Frosbite freeze to take effect immediately.

Because Frostbite only lasts for 4 seconds, a mage often only has enough time (due to lag) to cast one or two Frostbolt (depending on haste) before the effect wears off. However, if a troll mage casts Frostbolt in conjunction with the racial Berserking (thus reducing the cast time to 2.25 seconds or less) then they can have up to two chances to proc a Frostbite. Ice Lance can also be cast instead of additional Frostbolts, as it can allow several castings into a frozen enemy, which is advantageous considering that it does triple damage to frozen targets.