There are two scatter symbols in Books and Bulls. The one with the book triggers free games in which a symbol is chosen as a special bonus symbol. This symbol can then expand to all fields of the reel and, in the best case, create a full screen of the same symbol.
As the second scatter symbol, the bull can also trigger free games, in which all symbols with the torero are held on the reels as sticky wild symbols. This means that the number of wild symbols on the reels increases every time a torero appears.