Grounding Totem is a core shaman ability learned at level 38. It applies a buff to all party members within range every 10 seconds which effectively makes them immune to the next spell cast on them, except AoE spells. The spell will affect the totem instead, destroying it.
The totem is useful for shutting down mages in PVP. Simply [Wind Shear] to break their first cast, drop the Grounding Totem to absorb their second cast, and Wind Shear should be ready again by the time the mage can cast again.
It is also useful to place a Grounding Totem when healing as it can redirect spells that interrupt you.
Noteworthy when trying to escape a class that has spell-based snares, such as a mage's Frostbolt.
It is rare for a totem to absorb more than one direct damage spell. This can happen if the two spells finish casting before the totem is hit by the initial spell. Spells with a travel time do not damage the target until the projectile hits; the totem will redirect any of these types of spells until it takes damage and summarily is destroyed.
Grounding totems do not tend to work against boss abilities that mind control players. However, they do work against monster-initiated mind controls. The same is true for fear effects. Direct damage effects and curses are generally groundable, even if from a boss.
Patch 6.1.0 (24-Feb-2015): Grounding Totem now protects both party and raid members (up from only party members). Additionally, fixed an issue where Grounding Totem was incorrectly redirecting Provoke (Monk), Growl (Hunter Pet), and Defile (Death Knight).
Patch 6.0.2 (14-October-2014): Totems will no longer cause hostile creatures to enter combat with the Shaman based on proximity.
Patch 5.1.0 (27-Nov-2012): All totems are now considered spells, and summoning totems can be prevented by silencing effects. Searing Totem, Magma Totem, and Fire Elemental totems fall into the Fire school, while all other totems fall under the Nature school.
Patch 4.1.0 (26-Apr-2011): Grounding Totem cooldown has been increased to 25 seconds, up from 15.
Patch 3.2.2 (2009-09-22): Grounding Totem will now properly protect against the Death Grip spell.
/Patch 3.0.2 (14-Oct-2008): All totems are now considered on the "Physical" school, and no longer magical spells.
Patch 2.4.0 (25-Mar-2008): The Global Cooldown of all Totems has been reduced to 1 seconds, down from 1.5 seconds.
Patch 2.3.0 (13-Nov-2007): This totem is now destroyed upon redirecting any spell to itself.
Patch 1.11.0 (20-Jun-2006): This totem will no longer reflect the Mage talent Combustion back onto the Mage.
Patch 1.6.0 (12-Jul-2005): Fixed graphical anomalies when using channeled abilities in a group with a grounding totem.
Patch 1.5.0 (2005-06-07): Fixed a bug that allowed some area of effect spells to be "grounded" and/or destroy the totem.
Patch 1.4.0 (2005-05-05): Should no longer redirect area effect spells or be destroyed by area effects spells.