The four ways to put a monster down
When you play a monster from your hand you choose the position (Attack or Defense) and whether it enters face-up or face-down. That is four combinations:
| Position | Face-up | Face-down |
|---|---|---|
| Attack | Can attack; everyone sees the card. | Can attack; the opponent only sees the card when it is revealed. |
| Defense | Does not attack; defends with its DEF. | Does not attack; defends with its DEF and is only revealed in battle. |
Revealing
A face-down monster is revealed when it attacks or is attacked. Changing the position of a face-down monster also reveals it.
Choosing the constellation
Every monster has two constellations. When you summon a single monster card, you choose which one is active; the choice decides who has the advantage in battle (Constellations). The monster born from a fusion enters with the first constellation of the resulting card: the screen only offers the choice for a single card.
Attacking
Each monster in Attack position attacks at most 1 time per turn. A monster in Defense does not attack. A freshly summoned monster can attack the same turn, except on the starting player's turn 1.
Changing position
Each monster can change position 1 time per turn and not after it has attacked. Going from Defense to Attack is how you prepare the next turn's attack.
Fusing with a monster on the field
A fusion can use a monster already on your table as the first material; see Fusion.