Among the sorceries and incantations in the Lands Between, there are those that are deemed legendary spells. These are the most powerful of all the spells you can obtain, and the Elden Stars incantation is among them. This incantation creates a mass of shooting stars that assail the area and strike your opponent. This incantation can deal a ton of damage when all of the stars hit. Here is how you can get the Elden Stars incantation in Elden Ring.
To obtain this incantation, you will first need to reach the Deeproot Depths. This is one of the late-game areas that are underground. You can only reach this area in two ways; from the Capital City sewers and from the Siofra River Aqueduct dungeon. The easier method is to go through Siofra River. Once you reach the aqueduct, go through the dungeon and defeat the Valiant Gargoyle boss. Once this boss is defeated, interact with the coffin at the bottom of the waterfall to get a cutscene. At the end of the cutscene, you will arrive at Deeproot Depths.
Once you reach Deeproot Depths, go to the area where all of the roots are intertwining with each other over the chasm. Use the roots to reach a cave on the cliffside. There will be a large number of ants inside so be prepared to deal with them. Go through the cave to reach the cliff on the other end where there are some flying ants. You will be able to grab the Elden Stars incantation from the cliff. Make sure to deal with the ants first since they can be a pretty big threat.