Well it's self-explanatory
Imagine a medieval aged kingdom, the citizens sided with the witches to kill the king
"crown the witches" simply mean follow the witches (instead of the king)
Oh,thank you nazaka!
It's very understanbable.
I had thought that this thread tytle means that "Kill KingArturia!(Not the person in legend,but the person here)" ,and thought that "How violent joke it is!".
Well it's supposed to be just "Kill the king, crown the witches" (without "[MENTION=29421]King[/MENTION];)
But there's someone here with "king" in his/her username so why not XD