After Main Phase 1 has ended, the turn player may choose to enter the Battle Phase. If they choose not to, the player automatically proceeds to the End Phase. They cannot enter Main Phase 2 unless they conduct their Battle Phase.
During the Main Phase, the turn player may:
- Normal Summon/Set a monster (the player can only perform one Normal Summon/Set per turn, so the player cannot Normal Summon/Set in both Main Phases).
- Special Summon a monster(s).
- Manually change the battle position of a monster, provided that monster did not declare an attack during the Battle Phase, it was not Summoned or Set during that same turn, and it has not already manually changed its battle position that turn.
- Flip Summon a monster, provided it was not Summoned or Set during that same turn.
- Activate Ignition Effects, such as those of "Barrel Dragon" or "Cannon Soldier".
- Set Spell/Trap Cards.
- Activate Spell/Trap Cards of any Spell Speed. Quick-Play Spell Cards and Trap Cards cannot be activated in the turn they are Set.