To trigger the Big BuildUp feature, you need to land a feature activation symbol on either the second or third reels. The Big BuildUp will activate at least one of your feature rewards that you have been keeping in storage on the shelves right next to your grid. You can learn more about these in the main part of this review of Fire Gnomes slot. The Big BuildUp can give you silver or gold prizes, or wild multipliers up to 5x and additional wild symbols may appear regularly alongside them.