The Dung Eater is a nasty villain in Elden Ring, but you can one-up him by transforming him into a lifeless puppet and using his spirit ashes to summon him as your own personal enforcer.
Getting access to the Dung Eater spirit summon is pretty simple to do, but it does require working with one of the strangest characters in the game. Preceptor Seluvis is a sorcerer that you can meet after speaking with Ranni the Witch at the top of Ranni’s Rise in the back of Caria Manor. Once you’ve exhausted Ranni’s dialogue at the Rise, you can head to the tower next door where Seluvis is waiting for you with a stomach-turning proposition.
Seluvis uses a special potion to transform people into his personal puppets. When you speak to him, he has his eye on Nepheli Loux, a warrior you might have met at Stormveil Castle or Roundtable Hold. Seluvis gives you his potion and asks you to feed it to Nepheli, so he can have her for himself. Instead of doing that, you can give the potion to the Dung Eater. If you do, when you come back to talk to Seluvis, he’ll sell you the Dung Eater’s spirit ashes for five Starlight Shards. From then on, you’ll be able to summon the Dung Eater to aid you in battle.
Finding the Dung Eater’s body
Look, you and I both know that doing anything to help Seluvis is beyond evil, but the Dung Eater is evil himself, and summoning him as a spirit is really cool. Let’s set aside morality for a moment here and just get into it. You’ll first meet the Dung Eater at Roundtable Hold, but you need to find his real body out in the Lands Between before you can convert him into a puppet.
When the Dung Eater appears in Roundtable Hold, you need to bring him a Seedbed Curse. Once you do, he’ll give you the Sewer-Gaol Key and ask you to find his real body in Leyndell. The Dung Eater’s body is locked in a cell in the Subterranean Shunning Ground.
Fast travel to the Underground Roadside Site of Grace and take a left. Walk until you find a sewer grate you can jump down. You’ll find yourself in a grimy tunnel, and at the end of it is a ladder that takes you up to the locked door you can open with the Dung Eater’s key.
Get through the Dung Eater’s dialogue here, and you’ll have the option to give him Seluvis’s potion. Be warned, this will block you from finishing the Dung Eater’s questline, but you are free to kill him here to get his armor set. After all that you can head back to Seluvis’s tower. He’ll talk to you about how Nepheli still hasn’t shown up to be his puppet, but then he’ll give you the option to buy the Dung Eater’s spirit ashes.