If I move a unit into a contested battlefield, then I use Stupefy, then my opponent also uses Stupefy. After resolve, I use Bellows Breath. Where is the focus now?

Here's the ruling:

Focus goes to your opponent (P2) after the Stupefy chain resolves. You can only play Bellows Breath if your opponent then passes.

Here's the full sequence:

1. You move into a contested battlefield. Your unit applies Contested status. A Combat Showdown begins. Per Rule 345, you gain Focus as the player who applied Contested.

2. Showdown Open State — you have Focus. You play Stupefy (Reaction). The Chain closes. You have Priority as the controller of the newest Chain item.

3. You pass Priority. It passes to your opponent. They play Stupefy (Reaction) on the Chain. They now control the newest item.

4. Both Stupefies resolve (LIFO — opponent's resolves first, then yours). After yours resolves, the Chain empties.

5. Focus passes. Per Rule 340.2.a and Rule 346, when the Chain empties in a Showdown, Focus passes to the next player in turn order — your opponent. This exception does not apply (the Chain opened from voluntarily played Reactions, not from triggers).

6. Showdown Open State — opponent has Focus. They can play an Action/Reaction, activate abilities, or Pass.

7. If they pass, Focus passes to you (Rule 347.4). Now you have Focus and can play Bellows Breath (Action — legal in Showdown Open State).

Bottom line: You cannot play Bellows Breath immediately after the Stupefy chain resolves. Your opponent gets the first opportunity to act. Only if they pass does Focus return to you.