The following glitch requires the Succubus Soul and the Cutall weapon. Go to the final save location in the Abyss and do the special attack on the very end of the wall, not near the door. Keep doing the special move until you fall out of the level. You can return to the save room. If you have a 100% map completion, you will uncover about 56% more if you manage to get back in the save room. Note: If this is done, you will make the final Boss impossible to defeat. After you defeat him, he will just respawn.