It triggers the spin at the maximum allowed values. If two or more Special Expanding symbols occur on reels during free spin round, all symbols on corresponding reels will be converted into Special Expanding symbols and your winnings increase! Bookof Ra slot is one of the first games on this topic. Games on the Egyptian topic are very popular in many online casinos. You can also use the Auto spin option. Book of Ra Tricks page before you do that. Symbols, Winnings, and Bonuses, the highest paid symbol is a portrait of a hero, who looks like Indiana Jones. You can either take the prize or try to guess again. Meaning that when they appear on the reels, they will extend to cover the whole reel.