Viper School

The School of the Viper is one of the three schools introduced in the Witcher 3, specifically in the "Hearts of Stone" expansion of The Witcher 3: Wild Hunt.

The School of the Viper lies in the keep of Gothur Gvaed in the Tir Tochair mountains within the Empire of Nilfgaard. A secretive witcher school, it fell into ruin at some point before the events of The Witcher 2: Assassins of Kings. The circumstances caused its downfall are not mentioned by Letho in his account to Geralt during the Epilogue.

Students or adherents of the school include:

An unknown witcher from The Witcher outro
Auckes
Ivar Evil-Eye
Kolgrim
Letho of Gulet
Serrit
Two unnamed witchers mentioned by Letho in his conversation with Geralt at the end of Chapter III

It is also possible that the mysterious assassin from the end of The Witcher may have been one of the two unnamed members, rather than a third.

What we do know about the school is that its members have become outcasts within the Nilfgaardian Empire since the school's downfall. Before its destruction it had a huge collection of books about the Wild Hunt.

It is interesting to add that the school might have differed from other witcher schools in its swordsmanship training, as it seems that almost all witchers belonging to the Viper School (except Letho) used two short swords in combat as their weapons of choice, as opposed to the traditional usage of two-handed swords preferred by other schools. However, all witchers known to use short blades were Kingslayers, and it is possible that they chose to forfeit using their long swords for the more compact counterparts to better serve the purpose of assassinating kings of the North. Whatever the truth, these witchers possessed exceptional skill in wielding short blades, and their skill in swordsmanship was rivaled only by that of Geralt.

In The Witcher 3: Wild Hunt, there is also a set of Viper School gear available for crafting.