[Spoiler]Beating the final boss of BaW is impossible

[Rafaelbw]

He is immortal. He can take any risks(except when fighting against another higher vampire), so going full nuke against a witcher seems fair enough.

 

[gregski]

What I noticed yesterday is that casting Aard into the bat swarm just spreads them out and you're alive and safe. IT requires perfect timing though.

 

[Aridea]

I found an Ekhidna Decoction to be a real help on my sword-based heavy-armour version of Geralt (with heavy use of Quen casting).

Coupled with some enthusiastic running around to dodge various special attacks, of course. I should perhaps add that dodging doesn't have to be reactive. The enemies aren't smart enough to predict movement (as far as I can tell) so if you just keep moving when you're unable to damage the boss there's a good chance any (ranged) attacks will miss you.