I'm not an expert on it, Humplemann is.
As far as i know if you keep on winning or paying the "gem tax" 10,20,30 etc until it is capped at 250, your streak keeps on advancing until it reaches 98 and the next 98 are doubled the stated value, the next 98 are tripled, then the next 98 quadrupled and so on until the maximum of x10 is reached where it stays. It obviously costs a lot of gems (3000ish) to reach the 250 cap. I'm not 100% sure the figures are right but basically the longer your streak gets, the greater your rewards in coins, seed packets and gauntlets etc...
I think i read a post where someone got a 60 seed packet for shadow peashooter and with his x10 multiplyer it became 600.
