Can you save Blackguard by killing Dung Eater?
Once you have defeated the Dung Eater during his invasion and you have fed Dung Eater’s corporeal body Seluvis’s Potion and/or killed him in his cell (in which you can do both to obtain the Dung Eater Puppet and the Omen Set simultaneously), head to the Church of Vows to absolve your sin and make Boggart friendly again . Unlock the door and speak to the Dung Eater, commanding him to leave his cell. It can be tempting to kill him here, given what he informs you he’s planning to do, but you must resist the urge if you’re going to complete this quest.You can save him by aggroing him before freeing Dung Eater from his cell. After he is aggrod you can go to Dung Eaters cell and free him then go back to Blackguard and approach him to get aggrod again so you can trigger Dung Eaters spawn. Kill Dung Eater and go to the Church of Vows to clear your sins.