After the expansive second quest i.e. The Beast of Toussaint, this quest will appear too short to some. However, Blood Run is nonetheless a main quest even if it has just one main beast you need to beat.
The Witcher 3 Blood and Wine Quest Blood Run
In this quest you take on Detlaff and try to beat the beast before Regis interrupts regardless of who has won. It is very tough to beat this one, but you can try if you have Geralt at a stronger level.
Fight The Detlaff
You will be in a building in Beauclair where a conversation with The Beast of Beauclair will lead to a fight.
If your character is strong enough, take him on with Black Blood potion, Vampire Oil and the Quen sign. The Detlaff is quick and agile, so keep moving, thee best time to attack is when it is preparing to attack or lands a failed one due to Quen.
If you win, you get additional XP, but don’t worry even if you lose a cutscene will start and bring in Regis.
Regis being Geralt’s old friend, will have a conversation where Regis will reveal to you that the beast is actually Detlaff van der Eretein. This is where Regis asks you to help locating for him – a task that will be taken on in the next quest i.e. La Cage Au Fou.
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