Slayer of Souls achievement in Cult of the Lamb

You get access to Purgatory after completing the main objectives and talk to "????" at the end of the game. You get the achievement for completing the 6 runs of one Fleece on either "Boss Rush" or "Dungeon Gauntlet" one fighting all bosses as a well... boss rush, and the other being a run through the dungeon until you fight The One who Waits. After defeating him you get the achievement.

- If you're not great at dodge rolling don't be ashamed to lower the difficulty before starting any of the Purgatory runs, Easy, Medium, Hard it gets you the same achievement.

- After getting all the upgrades from doing Sermons it will reward you with a Blue Heart every day you do a Sermon which carries over to Purgatory, I know you can have at least 3 rows of hearts if you REALLY want to be sure you don't fail. (Just know farming heart will take a while as Sermons are once a day just like Purgatory runs).

- Choose a good path if you're doing the Dungeon Gauntlet, meaning choose Heart Rooms if you need them, avoid conflict if needed, and pick weapons and relic rooms if you're not familiar with or don't like the ones you currently have. (I recommend Hammers or Gauntlet/Fist weapons, as well as Hounds of Fate as a Curse, and damaging relics like Clauneck's Shoe as it does good damage and gives you invincibility frames for the animation when you use it.)