To take this one step farther, the rules state that a player may play one card on their own turn, and one card on the opposing player's turn. Since each round consists of potentially both players taking more than one turn each, I interpret this to mean that a player may play more than two cards during a round of play.
For example, Player 1 has four units, and four command cards. During his first turn, he activates two of the four units, playing one card. During Player 2's first turn, Player 1 plays another card. When it comes back to Player 1, he'll activate his last two units, and may play another card. When Player 2 takes his last turn of the round, activating his last two units, Player 1 may then play his fourth and final card.
Dal forum della FFG riporto questo stralcio di discussione su quante carte comando possano essere giocate durante un turno.
Se ho capito bene quanto dicono, distinguendo i termini tecnici round e turn, io posso usare più di una carta comando per singolo round di gioco ?