The event is not rigged .. First 20 spinning times gives items and a chance to win an early Ultimate Tool Essence while the 21st spinning attempts grants the sure 1 Ultimate Tool Essence .. I've experienced having 2 Ultimate Tool Essence with using 1050 keys before and i assure you that it's a chance .. It's not rigged but it's the requirement to get the said reward .. This event has been at cycles for years now, you should know by now before saying the event is rigged ..