I haven\'t found one of the new ones, but earlier in the beta they were just like normal potions + some special bonus. You set one to your default potion and just used it like a normal potion. No need to stack. In theory you could carry normal pots and a legendary, or more than one type of legendary and use different ones as needed, though whichever you drank all of them would be on cooldown for 30s.
Since only one can go on the hotkey, you\'d have to put the others in Inventory and right click to drink, which wouldn\'t be real convenient for emergency use.