Page 2 of the Tournament Rules state that:
A player cannot bring more than one copy of each component - 12 deployment cards.
The core set has 12 deployment cards but 3 of them (Advance, Ambush and Detachment) are duplicated. If players are forbidden to bring duplicate cards, how many should they bring to the tournament?
Each expansion adds a different deployment card, so at most only 11 unique deployment cards can be fielded.