I went for the mystery choice and got the 15 spins starting at x10, while that other win from back in November was also from the mystery spins, that time a 5-scatter 19/10. I used to ignore the mystery option before, but now I always choose it and generally find the results much better (or less worse) even without these two wins in mind. You'll get a lot of the 5/1's, sometimes even 4-5 of them in a row, but the 15/10's,15/5's, or 10/10's aren't that rare. I also play with the ante bet enabled and over a fairly large sample size, I found this slot to consistantly scatter once in every 150 spins.