The wild symbol is represented by 3 magic boxes of different colors that for the base game only work as substitute for standard symbols, but during the free spins round additionally they have a win multipliers that vary depending on their color this way: red - 2x, green - 3x, and blue - 4x.
The round of free spins is triggered when 3, 4 or 5 scatters, identified with the image of the black billiard ball marked with the number 8, appear simultaneously on any position on the reels, which give 8, 16, or 24 spins respectively, in addition to an instant payment made in accordance to the paytable.
The concept established by Microgaming for special features incorporated in Magic Boxes is quite interesting, but to be honest, I think this game has not achieved greater popularity among players due in large part to its tight paytable. To get an idea, we can see that the symbol of the hat, which is the highest symbol throughout the game, has a payout when you get 3 of a kind barely equivalent to your total bet, for any profit with this symbol you have to get at least 4 of a kind; the lowest symbol, which is the number 9, just equals to your total bet in case of obtaining 5 of a kind. The other factor that contributes greatly to the low winnings average, in my opinion and based on my personal experience with this slot, is the difficulty to trigger the round of free spins, which is the section of this game where the most of the action is concentrated. Just a fairer paytable would make of this slot machine a totally success.