This is the problem , players say they have white wolf and how they got it, but others try and fail, because its based on assumption and not fact.

Those that have them..... 

.....and know the real reason why.

Well all i can say thats what i did and i got it

Interesting.

I have no reason to doubt what you say, and none to confirm your suggestion either.

However, this is at odds with what other players have claimed concerning this achievement, whereby low level palaces have White Wolf, and those that claim to have got it without doing as you suggested, but again I have no evidence either way on such claims.

I have white wolf, yet never killed a snowking, so that is not it.

I personally cannot confirm your suggestion for the Troll is incorrect,but I think you are barking up the wrong tree.

Of course, Game of Thrones aficionados, may have made the same connection, but perhaps  ghosts only go boo.