I know it's about ten minutes. But does the cooldown begin from the time you consume the Three of Coins? Or does it begin when you kill an Ultra? Or does it begin when you successfully get an Exotic engram? I just find it confusing and want to make the most efficient use of my time. Thank you! (P.S. If there is a cooldown timer, why don't they just make it visible for you to see in your Inventory screen? Why make it invisible and all 'secretive'?)