Greatmother Geyah the ailing spiritual leader of the Mag'har, located at the Horde outpost of Garadar in Nagrand. Formerly of the Frostwolf clan, she was the mate of one chieftain (Garad), the mother of another (Durotan), and the grandmother of the former Warchief, Thrall.
The Red Pox
In the early days of the Horde Geyah, rather than abandon the afflicted, established a quarantined settlement in the region of Nagrand, hoping to care for the victims while limiting exposure. Among Geyah's patients were the children of several chieftains, including Garrosh Hellscream and Jorin Deadeye. As the clans gave the settlement a wide berth, the orcs therein were not forced into joining the Horde or the Blood Pact with Mannoroth. From afar, Geyah watched in disgust as the brown skin of the Horde turned a sickly green and once-verdant lands died. However, Geyah and those in the village, sickened though they were, remained mag'har, uncorrupted.
Shortly before Draenor's destruction, Geyah was visited by Kargath Bladefist, who had stumbled upon the village by accident and demanded that every able-bodied warrior come to his aid in assisting Ner'zhul's nefarious plans. Geyah, naturally, refused to aid her corrupted brethren, not that she could have anyway, as most of the village was still suffering from the Red Pox. ( )
After completing a large series of quests in Nagrand players are sent to Geyah to help communicate with the spirits of the land and heal them. Once this quest line is complete she will converse with the player about Garrosh and his fitness to lead. She will state the player reminds her of her son Durotan. Upon hearing this name your conversation will then tell her of Durotar and of the leader of the horde, Durotan's son, Thrall.
In a quest line, Geyah instructs the player to "go to my grandchild", Warchief Thrall in Orgrimmar, and inform him "his blood is here — in this shattered world", and that "his father's legacy lives on." Thrall sends the player back to her, to "tell her that her grandson comes".
After the of his visit to Nagrand, Thrall will sit down with the Greatmother. Some time after, Greatmother Geyah will despawn. As she was already dying of old age, this may mean that she finally passed away in the presence of her grandson. She will respawn immediately after.
Lords of War
In Lords of War; part 3, Geyah was bitten by a drift lurker, therefore putting her into a deep coma. When Durotan went into a fit of Bloodlust, she finally brings Durotan back to his senses after he kills Stormfang, by calling his name.
Her name may be derived from the Goddess Gaia, Mother Earth in Ancient Greek Mythology and Grandmother of the chief gods.