Direct answer: The Marionette spawns when the Jack-in-the-Box music completes for the third time. Rewind the box in time to prevent the fight; if you are pursuing Last Performance, allow the spawn and kill the Marionette with the weapons available in the run.
What is confirmed
Steam officially recognizes Last Performance — Kill a Marionette. An official six-player update also says Marionette health was lowered, confirming that the enemy has a combat and balance layer affected by lobby scaling.
Prevent the Marionette from spawning
Community guides consistently connect the Marionette with the Jack-in-the-Box objective:
- Listen for the music during the documented Night 9 event.
- Find the music box before the third play completes.
- Hold the interact control to rewind it.
- In co-op, divide the possible rooms instead of duplicating one search path.
How to kill the Marionette for Last Performance
If the third play completes, switch from the search objective to combat. Keep distance, use the emergency weapons available by this point and focus fire until the Marionette is defeated. Current player reports also mention a landmine as an effective option, but they do not support a universal ammo count or guaranteed damage number.
This branch is intentional only when you want Last Performance — Kill a Marionette. For an ordinary safe run, rewinding the box before the third play is the cleaner outcome.
Why the guide stays conservative
The available official material confirms the Marionette name, achievement and later health adjustment, but not a complete public move set. Community sources agree on the music-box trigger and that the spawned enemy can be killed, while exact ammo requirements vary by report. This page therefore avoids unverified health numbers, spawn timers and guaranteed room sequences.