I have just completed a game, and I was very surprised to see that the witch could 2 take gold, choose not to bewitch anyone, and build.
It seems contratry to the rules, as stated by Bruno Faidutti on his website (http://www.faidutti.com/index.php?Module=mesjeux&id=328&fichier=105) :
"Q: Are the character special abilities compulsory?
A: No. The assassin is not bound to kill, the thief is not bound to steal, a.s.o.
The only exceptions are the Witch and the Navigator"
So?
