The Main Phase (メインフェイズ, Meinfeizu) is a term used in the Genso Suikoden Card Stories TCG. It is the very first phase of a player's turn.
Overview
In the Main Phase, the player has three options.
Discard
The player can discard any number of cards from their hand, once only. They can then choose to replenish your hand by immediately jumping to their Replenish Phase. In general, players will almost always want to keep Leader cards in your hand and dispose of superfluous Mission or Facilities cards.
New Mission (Begin a Battle)
The player can play a new Mission or Facilities card and begin a new battle, beginning the Deploy Step. Only 1 Mission card can be played at a time. The opponent deploys first to the mission and control passes back and forth until the mission is cleared or cannot be resolved by either player.
A new Mission or Facilities card cannot be played if there are 2 unresolved Mission or Facilities cards in play by the player already. No more than 4 unresolved Mission or Facilities cards can be in play (2 per player).
Continue Mission (Continue a Battle)
If a Mission or Facilities card has been unresolved due to a lack of cards or a card effect prematurely ending an engagement, the player can select an unresolved card and continue a battle.
The player who selects the mission begins the battle by playing a character card, beginning the Deploy Step. A player is not allowed to pass their first turn in their select continued mission. Control then passes back and forth until the mission is cleared or cannot be resolved by either player.
Ensuring that you can mostly likely win the card with your current hand is a key part of the game, in order to avoiding wasting valuable manpower.
Following the Main Phase
Once the Main Phase (and the battle steps within in) ends, the game moves onto the Replenish Phase.