Wave-O-Meter and The Book of Wilds are two of the game's exclusive features that add a lot of cash to the game; they together create the most deadly combos.
It's easy because the reels fold, so why your symbols disappear instead of staying in place. Every time you make a winning combination, there will be more after that, which fundamentally opens up the wave of infinite loops and the possibility of victory. At least this is theory, sometimes it does happen, but most of the time you get the smallest win.