How you get here
Defeat Isaac in Cathedral and use the post-fight chest while carrying The Polaroid on the standard route.
Prepare before the checkpoint
- Compare the starting Locked Chests with your key supply.
- For Mega Satan, check both the golden-door unlock and a suitable opener.
- Do not treat the normal ??? arena and Mega Satan's door as the same objective.
Related item rules: route tools and exceptions mentioned in this guide. Read each effect before relying on it.
The PolaroidCheckpoint and exit
Defeat ??? for the upper-route completion target.
Mega Satan is a separate unlocked-door encounter. Other special exits can create additional route choices.