The free spins round is triggered when you land three or more scatter symbols. The scatter can appear on any reel, but it will never be a double, or triple split symbol. You will automatically be awarded 10 free spins when landing three or more scatters. When the free spins round launches, one of the boost symbols is randomly selected. This will then show up on reel 6. Whichever boost is selected will then sporadically appear more often than the other boost symbols during the free spins round.