Magatha Grimtotem is a corrupt leader of the Tauren race. She is the Elder Crone of the Grimtotem, a tribe of honorless and ruthless Tauren.
Magatha obtained her shamanistic powers and a very young age, and craved even more. She eventually married the chieftain of the Grimtotem Tribe, but many believe she had arranged the entire marriage herself. Losing her husband after he fell to his death, she became the new leader of the Grimtotem. She and her tribe believe they will eradicate the lesser races of Kalimdor and take over the Tauren race for themselves.
Magatha had plotted for years to kill Cairne, and finally came up with an idea. Thrall, Warchief of the Horde, had given Garrosh Hellscream the throne so that he could help the Earthen Ring. Cairne did not approve of this, and challenged Garrosh to a duel. Magatha had "blessed" Garrosh's axe but poisoning it. With one slash, Cairne had died and Magatha had command over the Tauren city of Thunder Bluff. Her rule was short lived, however, as Baine, Cairne's son, formed a rebellion and exiled Magatha and the Grimtotem and Tauren not loyal to the Horde from Mulgore.
It was finally revealed that Magatha had been captured by the Twilight's Hammer Cult and was going to be used as a sacrifice. She used her pet wind serpent to find a member of the Horde or Alliance that could help her escape. She would send them on trials to kill her top lieutenants (the last one being her own nephew) - should they all be defeated by a single chosen one, Magatha would lure them into the Twilight's Hammer base to free her.
Upon being freed, Magatha sent her chosen one to slaughter the remains of the cultists and stop their plans to destroy the entire region by using a primal elemental named Animus that had a destructive artifact called the Doomstone. Once this was complete, she left the Thousand Needles with the Doomstone and swore that if she met her "chosen one" again, she would kill him/her.
Relationship with the Forsaken
Magatha seems to have had a temporary alliance with the Forsaken. Like the rest of the Tauren race, she pities them and seeks to find a cure of Undeath. Sadly, her research was in vain, for their friendship did not last long.