In order to summon jellyfish in Elden Ring, you need two things: the Spirit Calling Bell, and the Spirit Jellyfish Ashes. You also need to be playing in single-player. Get the Spirit Calling Bell either from Renna the witch at the Church of Elle (at night, and after you’ve got Torrent), or else buy it from the Twin Maiden Husks merchant at Roundtable Hold. To get the Spirit Jellyfish Ashes, you need to speak to Roderika at Stormhill Shack three times. The first time you speak to her, she’ll tell you that everyone she knows has had their body parts grafted to a spider, and will give you the Sitting Sideways pose. Speak to her again, and she’ll tell you how scared she is of having her body parts cut off. Speak to her once more and she’ll ask you to take “this little one” with you, and you’ll get the Spirit Jellyfish Ashes.
Related: How to summon other players in Elden Ring
To summon jellyfish, first map the Spirit Jellyfish Ashes to one of the slots in your pouch, then go to an area where summoning is possible. You’ll know when you’re in one because a gravestone icon will appear on the left edge of the screen. Now hold Triangle/Y and tap the D-pad in the direction to which you mapped the Spirit Jellyfish Ashes. This will summon a large spectral jellyfish that will fight on your behalf, although it’ll do so quite half-heartedly, to be honest.
