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Rivermouth Cave walkthrough: Elden Ring Shadow of the Erdtree

Here's how to complete this hidden away dungeon to get a powerful new Spirit Ash summon.

A warrior enters the Rivermouth Cave in Shadow of the Erdtree.
Image credit: Eurogamer/FromSoftware

The Rivermouth Cave is an optional dungeon in Elden Ring's Shadow of the Erdtree DLC. It's very well-hidden, lying tucked away on the Ellac River cliff face at the bottom of Gravesite Plain, but inside this short, simple cave there's a powerful new Spirit Ash to claim. To make sure you grab everything you need from this dungeon, read on below for our in-depth Rivermouth Cave walkthrough.

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Rivermouth Cave walkthrough

It's very easy to miss the Rivermouth Cave, as it's hidden away right in the top corner of the Ellac riverbed. You'll need to descend to the lowest level of Gravesite Plain to reach it, and you can get to it either by following the route to get to the Cerulean Coast, or by descending down the large stone slabs in the cliff from the Temple Town Ruins in the Ancient Ruins of Rauh.

The latter are the closest to the Rivermouth Cave's location, and you can see precisely where to find it on the map below:

A map screen from Shadow of the Erdtree showing the location of the Rivermouth Cave in Gravesite Plain.
Image credit: Eurogamer/FromSoftware

Activate the Site of Grace 'Rivermouth Cave', and head into the cave. You'll come to a room with several wolves in it. They don't put up much of a fight, so take them out and claim the 2x Hefty Beast Bones from the corpse at the end of the room.

Follow the path round, and turn right. This room is a dead-end, but once you've defeated the two wolves inside it, you can grab 3x Sliver of Meat from the corpse next to the wall.

That's it for this room, so turn back to where you came from, then head down the other path that's now on your right.

A warrior fights two wolves inside the Rivermouth Cave in Shadow of the Erdtree.
Watch out for the surprise wolf attack on your right. | Image credit: Eurogamer/FromSoftware

You'll come to a larger room with several wolves in it, who will jump down from the rocky platforms above you. Again, they're very easy to defeat, requiring just a couple of hits to go down. As long as you don't take on too many at once, it's a very straightforward encounter.

A warrior jumps up some rocky steps inside  the Rivermouth Cave in Shadow of the Erdtree.
Jump up these rocky steps to continue through the cave. | Image credit: Eurogamer/FromSoftware

Jump up the rocky slope and you'll see a corpse lying down below. As you drop down, the ground will also collapse beneath you, sending you further down to another chamber. Claim the 1x Shadow Realm Rune (1) that was on the corpse that fell down alongside you, then carry on forward down this new, blood-slick pathway.

Eventually, you'll come out to a large chamber and witness a very strange sight. A huge number of trolls all seem to be worshipping their leader in a large pool of blood, with one troll raising a large-red fork-shaped weapon into the sky. I wonder what they're all doing down there...

A warrior looks on a strange scene inside  the Rivermouth Cave in Shadow of the Erdtree, where trolls worship a stone altar on a pool of blood.
On second thought, I don't wanna know... | Image credit: Eurogamer/FromSoftware

You can go down and take them all on if you wish, but there are still more items to find before you move in. For now, crouch and stay silent, moving slowly and quietly round to your right. There are still a couple of trolls watching the scene from your level, so watch out for them as you move round the edge of the room.

A warrior creeps up behind a troll inside  the Rivermouth Cave in Shadow of the Erdtree.
Creeping up behind the trolls will help give you an advantage in battle. | Image credit: Eurogamer/FromSoftware

After taking out the troll round the corner on your right, head up the narrow passageway. There are some more wolves through here, but you can also find 1x Sacred Bloody Flesh on a corpse they're guarding.

If you continue to follow the path upwards, you'll arrive back at the chamber where you just fell from. You can choose to leave the dungeon at this point if you wish, but don't you want to find out what those weird trolls were up to? With all items now looted, head back down the way you just came and return to the chamber.

A warrior looks down to attack several trolls in a pool of blood in  the Rivermouth Cave in Shadow of the Erdtree.
Take out as many as you can from above where they can't reach you with their tridents and bleeding forks. | Image credit: Eurogamer/FromSoftware

Since there are so many trolls down here, taking them out one by one from a distance is defintiely recommended. Taking on so many at once up close and personal is a sure-fire way to get yourself killed, as their weapons can deal blood loss damage. For this reason, try and pick off as many as you can from afar, attacking them with a long-range weapon from the ledge you're on above them.

If you don't have a powerful long-range weapon, then you will have to go down and meet them face to face. Try and draw as little attention to yourself as possible, though, and only take on as many as you can manage.

A warrior faces two large trolls in a pool of blood in the Rivermouth Cave in Shadow of the Erdtree.
Only go down to the blood pool when you feel confident in taking out the remaining monsters. | Image credit: Eurogamer/FromSoftware

When every last troll is defeated, make your way to the stone altar they were facing and claim 3x Sacred Bloody Flesh.

Now, follow the blood pool round the corner, and you'll find yourself at the boss fog door. It's time to face this dungeon's boss: the Chief Bloodfiend.

Need more help? Improve your stats by finding all of Shadow of the Erdtree's Scadutree Fragment locations and Revered Spirit Ash locations. Alternatively, see which Erdtree bosses you've still got left to beat, and track down some great new early weapons to help you on your adventure.

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