When you’re under the Bar you have to finish a puzzle to get to the next step of the Raven / Void Sword puzzle. After putting the bone trophy into the wall, and your sword: Click the type of bone below to see how your puzzle needs to be rotated.
Rotate:
Inside: - times Outside: - timesHow to start the Void Sword puzzle
After unlocking Pack-a-Punch, you can play until round 10 to get a Stamp from a bucket head/Bastard Zombie.
Once you have this, head to the statue room and interact with the statue with a Raven on it.
Once you have this, head to the room behind the Stamin Up room, and look for a bone trophy on the shelf.
Once you have a bone trophy, head to the Spawn area, into the Bar and then downstairs. You will be able to insert your bone trophy into the wall. Interacting again inserts your Bastard sword. You now need to complete a puzzle of rotating the inner and outer ring (Q & E on keyboard / Bumpers on your controller) and find the matching pair of shape and star sign.
After this puzzle orbs spawn from the wall puzzle. Kite them to the void holes that spawn. Once 3 enter the void, the void turns into another orb and relocates. Follow it and again kite 3 more in. Repeat one last time.
Finally the void hole turns into another orb, travells downstairs and into the puzzle, and finally your void sword will be given back to you.
Here is a video guide for the Void Sword (From beginning to end):
