Here's a guide for those who never unlocked the secret level during their run through the main game. The Mooshroom Monstrosity is the final boss in the secret level ???. This level can only be unlocked after finding nine runes, one in each of the main levels in the base game. (Ten runes in total, one obtained from finishing the story for the first time.) First you'll need to visit the church/temple in camp. After you've completed the Obsidian Pinnacle for the first time, head to the right of your camp, where you'll find a broken nether portal. Head down from there and you'll find the church. Go in and interact with the plate in the wall on the far end. Now it's time to hunt some runes! Locations can be found in the link below. To save time you can save and return to camp after acquiring the rune. Difficulty doesn't matter here.https://www.polygon.com/guides/21278336/minecraft-dungeons-r...
Once you've found them all, head back to the church and place all your runes. The secret level should now be accessible on your map. Equip at least one of the following:
- Ocelot armor
- Corrupted Seed ArtifactUnequip everything else
, you don't have to have all the pieces, just don't use anything else. Now just run through the level with said gear, difficulty does not matter.
Update update: With the release of the new dlc this now seems to work as it should. Previous tips in spoiler if you have problems with this