In the White Balverine quest you must help the people of Knothole Glade to get rid of the balverines that are attacking the town.
You can use the following Fable Anniversary walkthrough if you have any trouble with the White Balverine.
Money: 6200 + 20
Renown: 800 + 285
Trophy: White Balverine Head
After you accept the quest you need to travel to Knothole Glade. When you arrive you can see that the gates of the village are closed and that a few balverines are attacking the villagers that are outside the gates.
Use this to your advantage by engaging the balverines with your bow from a safe distance. When they are all dead the gates open and you have to speak with the chief who tells you that a White Balverine is inside the village (it will probably come towards you even if the chief says hes near the warehouse).
Use whichever attacks you prefer, because you wont be able to kill it right now. Hit it ten times while dodging his leap attack (the Slow Time spell helps a lot).
After the battle the chief tells you to visit the wife of the last White Balverine hunter in the village, because hes too tough even for you and she might have additional information on how to defeat him.
The house youre searching for is on the hill where you can buy yourself a house. When you approach the house the White Balverine attacks again. Just like before, hit it a few times until he runs away.
After that, the wife reveals that the White Balverine is actually her husband and she gives you a Silver Augmentation to defeat him once and for all. At this point the White Balverine attacks again, but you only need to hit him five times before he disappears in the woods.
The augmentation that the wife gave you is very effective against the balverine, but its not mandatory to use it. Alternatively, you can use a weapon that already has a Silver Augmentation, like The Sentius Legendary Weapon that you can get from The Temple of Avo.
The chief tells you that the White Balverine is now in Witchwood Lake area, so you need to travel to that location. The last battle is different, because he can summon regular balverines to fight alongside him.
You can either slow the time or summon a creature to keep the balverines busy while you deal with the White Balverine.
Once hes dead you get his head as a trophy. Return to Knothole Glade and talk to the chief to complete the quest. He gives you Theresas Letter and The Bloodline book, and he tells you that you can now fight in the Arena.