Attacking with Zero Creatures

Question

Two questions about attacking:

1) If I have creatures in play, can I declare an attack and then declare zero of the creatures as attackers?

2) If I have no creatures in play, can I declare an attack?

I'm not sure why you would want to, in either case, but it seems like a weird rules case.

Answer 1

Every turn has a combat phase (unless some card like Fatespinner tells you to skip it). The game proceeds to the combat phase after you're done with the first main phase.

The combat phase consists of five steps:

• Beginning of combat — this phase is mostly for abilities that trigger at the beginning of combat; in multiplayer, you also choose which players will be "defending," though you don't have to assign any attackers at this point (then priority passes between players)
• Declare attackers — you choose attackers at the beginning of this phase (then priority passes between players)
• Declare blockers — you choose blockers at the beginning of this phase (then priority passes between players)
• Combat damage — damage is dealt at the beginning of this phase (then priority passes between players)
• End of combat — this phase is for resolving "at end of combat" triggers (then priority passes between players, and we move on to the next phase)

You choose your attackers during the "declare attackers" step. If you select zero attackers, the game skips the "declare blockers" and "combat damage" steps.

So, you will always get a combat phase, even if you have creatures but choose not to attack, or have no creatures. Any combat in which you don't attack won't include the "declare blockers" or "combat damage" steps, though.

Answer 2

Yes, there is always normally a Combat Phase, regardless of whether you have creatures or not.

You don't really "declare an attack." What you are doing is proposing to your opponent that you proceed to the next phase "combat" and leave the current phase by both of you taking no actions while the stack is empty. During the Beginning of Combat step, you can either cast spells (instants usually) that may create new attackers or do nothing, your opponent may cast their own spells possibly to tap your creatures so that they cannot be declared as attackers. After that is the Declare Attackers step. Then and only then is when you actually declare which if any of your creatures (if you have any) are attacking.

506.1. The combat phase has five steps, which proceed in order: beginning of combat, declare attackers, declare blockers, combat damage, and end of combat. The declare blockers and combat damage steps are skipped if no creatures are declared as attackers or put on to the battlefield attacking (see rule 508.4). There are two combat damage steps if any attacking or blocking creature has first strike (see rule 702.7) or double strike (see rule 702.4).

Answer 3

Yes to both questions

Indeed, if played correctly, you have an attack phase every turn, and if you cannot or do not want to declare any attackers, the attack phase would still happen. In practice and in the vast majority of cases, players instead implicitly agree on a shortcut to proceed to the next main phase or to the end of turn.

Note however that if you declare an attack with zero attacking creatures, that attack will not trigger any abilities like "whenever a creature attacks you", or "whenever you attack/are attacked" or anything of the sorts. The phase still happens, but no attack happens, even if you explicitly attack with zero creatures.