I know that buying black dice will be returned once dice are retrieved, but what about the black dice awarded as part of the reward for completing tasks? Are they returned? From where are they pulled? In a two person game, you only have three black dice available: are there pulled from this supply?
Similar questions revolve around black dice as rewards for being there first to reach a destination.
Yes, black dice are always returned at the end of the round.
Yes, black dice always come from the supply (only 3 available in a 2P game) so you want to make sure there is one available when you are awarded one for completing a contract, getting a city bonus, etc.