its not that you have a 50% chance but that your "base" chance (whatever it may be) is increased by 50% so if normally you have a 10% "base" chance then applying a 3oC would increase it to a 15% chance. but even then they dmg04 said, " We have found that Heroic Strikes do not currently grant higher chances for Exotics when using Three of Coins consumables, compared to Vanguard Strikes." which is ass backwards and ridiculous that they don't address this immediately. this game/company suck.