Règles complètes de Magic: The Gathering

505.1.

There are two main phases in a turn. In each turn, the first main phase (also known as the precombat main phase) and the second main phase (also known as the postcombat main phase) are separated by the combat phase (see rule 506, «Combat Phase»). The precombat and postcombat main phases are individually and collectively known as the main phase.

505.1a

Only the first main phase of the turn is a precombat main phase. All other main phases are postcombat main phases. This includes the second main phase of a turn in which the combat phase has been skipped. It is also true of a turn in which an effect has caused an additional combat phase and an additional main phase to be created.

505.2.

The main phase has no steps, so a main phase ends when all players pass in succession while the stack is empty. (See rule 500.2.)

505.3.

First, but only if the players are playing an Archenemy game (see rule 904), the active player is the archenemy, and it‘s the active player‘s precombat main phase, the active player sets the top card of his or her scheme deck in motion (see rule 701.22). This turn-based action doesn‘t use the stack.

505.4.

Second, any abilities that trigger at the beginning of the main phase go on the stack. (See rule 603, «Handling Triggered Abilities.»)

505.5.

Third, the active player gets priority. Players may cast spells and activate abilities. The active player may play a land.

505.5a

The main phase is the only phase in which a player can normally cast artifact, creature, enchantment, planeswalker, and sorcery spells. Only the active player may cast these spells.

505.5b

During either main phase, the active player may play one land card from his or her hand if the stack is empty, if the player has priority, and if he or she hasn‘t yet taken this special action this turn. (See rule 305, «Lands.») This action doesn‘t use the stack. Neither the land nor the action of playing the land is a spell or ability, so it can‘t be countered, and players can‘t respond to it with instants or activated abilities.