Chills the target with frost, causing (64.4% of spell power) Frost damage and reducing the target's movement speed by 50% for 5 sec. Maelstrom increases damage and duration up to 100%.
In addition to its significant direct damage (which is instant cast and does not reset the shaman's melee attack), Frost Shock also snares the target. In PvE, it's useful against runners, slowing their retreat if the shock doesn't kill them outright. It can also be used for kiting high level mobs in certain dungeon situations. Against ranged opponents (in PvP, casters and hunters), the shaman can use this power to stay up close to use melee. Against melee classes like warriors and rogues, shamans use this ability to maintain their distance.
Trivia
Previously, Frost Shock was considered the "I win button" of Shamans, owing to the ability to permanently snare other players, such as in the prior entry:
With a ridiculous combination of high-damage, an instant cast, an eight-second effect, and a six-second cooldown, it would be foolish not to constantly Frost Shock other players or mobs until a win occurs. Once they are within melee range, drop an [Earthbind Totem] against melee mobs/players (or grounding for casters) and hack away for an easy win.
[Earth Shock] is now available only to Elemental shaman. Enhancement and Restoration shaman should use Frost Shock in its place.
No longer generates additional threat.
Patch 2.3.0 (2007-11-13): Frost Shock is no longer subject to diminishing returns.
Patch 1.6.0 (2005-07-12): Targets that are immune to movement slowing effects will no longer be affected by Frost Shock's movement slowing effect. Damage will still be caused.
Patch 1.4.0 (2005-04-19): Now subject to diminishing returns in PvP. This is considered a slowing effect.
Patch 0.9 (2004-08-17): Slowing effect will now obey the standard stacking rules.