The first game of a match in each round is played on a fixed map. The maps for each round are written in the brackets page.
The losing team picks the map in following games from the map pool. The map pool is found in the General Rules thread.
Each team can veto a single map during a round, but not the fixed map of the round. Maps not in the map pool are automatically vetoed.
No map can be played more than once within a single round. This includes different "variations" of a single map, such as Pale Tooth Gorge and Green Tooth Gorge.
While registering for the tournament, the player may pick up to 3 heroes to play as or Random.
Players can only choose to play as one of the up to 3 heroes they have selected before the start of the tournament for each match and must let the other player know their pick before the match starts. There is no restrictions as to which of their pre-selected heroes they may use in any given match.
Random players must select Random for every round and announce their hero at the beginning of the match. Failure to do so will result in either a warning, a restart of the match or a disqualification based upon the judgement of the tournament organizer.
The picking order is explained in the Commander Choices section of the rules thread.