Can you have multiple copies of the same unit in play at the same time, including multiple copies of your chosen champion?

Ruling: There are no restrictions on the number of copies of a unit you can have in play at any time. This applies to all units, including your chosen champion.

Nuances:

• You can have multiple copies of your chosen champion in play simultaneously
• You can have multiple copies of any other champion (like Darius) in play at the same time
• Having multiple copies of a champion with abilities that trigger (like Kai'Sa's Conquer and draw) means those abilities trigger for each copy