If they guaranteed a shiny, even just at wave 50, alot more people would engage, but they'd probably still need more incentive for legendary; like a guaranteed at mid boss and end boss. I've personally settled on the idea that since this is a limited time event, drop rates should be equal to roughly 3 hours of gameplay. But this company, nor any these days, know what gaming is actually about. Its not prestige or elitism, or exclusivity. Those are literally the 3 worst ideas for gaming. Its not difficulty, its not money. Its about the art, the fun, the engagement, and making it worth players' time regardless of difficulty level. Special, limited events should always have higher drop chances, no exceptions. Higher difficulty versions of those activities should be going crazy with drops.