Veni Vidi Vigo is a short main quest in Skellige and part of Battle Preparations. The Wild Hunt can only be beaten with powerful magic, and Geralt has recruited every strong sorceress he can find, both the ones he likes and the ones he cannot stand. When a chance comes up to add Fringilla Vigo to the roster, he takes it at once.
Fringilla is Emperor Emhyr’s prisoner, held on his flagship anchored off the Marlin Coast in Skellige, and she probably would have stayed there for the rest of her days. But thanks to Yennefer’s pact with the Emperor, Emhyr agrees to let her go, on one condition: she has to help in the fight against the Wild Hunt.
The quest is mostly conversation, but meeting Fringilla again carries a lot of history for players who remember her from the books and The Witcher 2, and it is interesting to see her forced to work alongside the very sorceresses she once schemed against.