Rule 103.2.b.1
This includes your Chosen Champion. Example: A deck could include Volibear, Furious as its Chosen Champion and still include 2 more copies of Volibear, Furious in their Main Deck.
Loading Arbiter…
This includes your Chosen Champion. Example: A deck could include Volibear, Furious as its Chosen Champion and still include 2 more copies of Volibear, Furious in their Main Deck.