"The most fervent servants of the Horned Rat are known as Grey Seers. Raised from birth to serve their unholy master, the Grey Seers are the spiritual advisers of the Skaven legions. They commune with their horned god, offering advice and seemingly daring their leaders to discount it in favour of their own plots and plans. Who can argue with the will of a god? Who would risk his wrath by ignoring his emissaries"
- —Steffan Paulus Adelhof, Scholar of Wolfenburg
A Grey Seer carried upon his luxurious palaquin
The Grey Seers of the Order of the Grey Seers are the chosen grey-furred emissaries of the Great Horned Rat, unholy prophets of ruin and destruction capable of channeling eldritch energies in destructive ways, leveling armies with lightning, or summoning ravening swarms of rats, all for the sake of furthering the Skaven cause and bring about the Great Ascendency of their foul deity. As chief agents for the Horned Rat and the Priesthood dedicated to his worship, Grey Seers wield tremendous influence amongst the clans, and only a fool would ignore their council and to inquire the wrath of the Horned Rat's chosen.
The spiritual leaders of the Skaven Under-Empire, these grey or white ratmen are born with tiny horns that, along with the color of their fur, mark them as the chosen of the Horned Rat. Cloistered away from the rest of the Under-Empire, they are tutored in the Lore of the Ruin. Much of their time is spent in prayer to their horned god, seeking his favour and guidance against those that would seek to undermine him.
Though it may seem a less hazardous course, the path of the Grey Seer is as treacherous as the road followed by any Skaven in the Under-Empire; perhaps more so. Initiates are commonly killed during their apprenticeship, both by the rigors of their training, as well as by the duplicity of their peers. If the competition between Skaven in the warrens is fierce, then it is doubly so in the cloisters of the Grey Seers. The Skaven that survive their apprenticeship are perhaps the most dangerous Ratmen of all. Apprentices are required to walk the Labyrinth of the Horned Rat to be fully initiated into the Grey Seers, and should they succeeded in all of this, they prove their fitness to guide, or some would say rule the Clans to greatness.
Source
- Warhammer Armies: Skaven (7th Edition) -- pg. 41.
- Warhammer Fantasy Roleplay: Children of the Horned Rat (2nd Edition) -- pg. 69.