Notes

In his pursue for Ciri, Geralt has to get aid.

He needed something powerful. More magical than anything they've encountered before. So he and Vesemir go to a completely different world to seak said help from a mage.
A wizard they call him. Yen referred to him as Gandalf the Grey.

Little did they know that the help they were seeking was in a different form. Not a spell or a magical object.