Then you have a free game feature that activates when 3 or more scatter symbols appear anywhere on the reels at the same time - you have 15 free spins with dynamic multipliers. The multiplier starts at a random value and ranges from 2x to 5x.
After each winning spin, the multiplier is stepped from its initial value until it reaches 5x. A non-winning rotation that reduces the multiplier by one step until it doubles. Basically, the multiplier will increase and decrease during the free spin, unless you win or lose.