After gaining knowledge in the game, finishing Ranni’s questline and ending, and basing my theory on the original Theatrical trailer, I’ve arrived at the following conclusion of who shattered the Elden Ring:
What we know for sure from the game’s text and dialog:
Ranni indirectly caused the shattering by murdering herself and destroying Godwyn, the Golden’s soul. Transforming him into the Prince of Death. This event sparked a great conflict that tore the Territories Between apart, with all of the Shardbearers wielding the Great Runes that comprised the Elden Ring, destroying the lands in what seems to be an age-long battle for power. Ranni is the Carian Royal Family’s Lunar Princess who previously revered and studied the Stars and Moon. She was a Shardbearer of the Golden Order but cast down her rune when she burnt herself on the Carian Divine Tower. Half of the mark is the Mark of Death on her face, while the other half is what murdered Godwyn, the Golden’s soul.
What I believe was her motivation was as follows:
Ranni is the one who initiated the shattering of the Elden Ring. She accomplished this to release the Lands Between from the Greater Will’s dominion. The Greater Will, and the Erdtree that sprouted from the Elden Beast it dispatched, appear to be a parasitic organism of the cosmos. It is likely that Ranni, as the Lunar Princess, sought to free the Lands Between and restore the power of the Stars and Moon, which provided power to the people of the Lands Between who studied them before the age of the Erdtree. They were not a direct power on the world who directly influenced it, but rather the people drew power from them.
But, it appears that Marika shattered the Ring in her grief following the release of The Prince of Death, as suggested by the flavor text on Marika’s Hammer, which reads:
Stone hammer made in the lands of the Numen, outside the Lands Between. The tool with which Queen Marika shattered the Elden Ring, and Radagon attempted to repair it.
The hammer partially broke upon shattering the Ring, splintering with rune fragments.
The following are the reasons I’ve come to this conclusion:
Ranni, the Lunar Princess, was one of the Shardbearers who, in disobedience of the Greater Will, burned herself atop the Liurnia of the Lakes heavenly tower, sacrificing her own life. To save her life, she transforms into Ranni, the Snow Witch, and takes on the form of a doll, which you’ll find out throughout Renna’s Rise questline.
Ranni’s plot involves her pursuing what appears to be retribution against the Two Fingers, who represent the Greater Will’s dominion over the universe and the Golden Order. Despite her past as a Shardbearer, she aims to destroy these objects for unknown reasons.
The Greater Will, which governs Queen Marika and Radagan of the Golden Order, is revealed at the end of the game to be a creature known as the Elden Beast. This creature looks to be an Extradimensional Entity. This event leads me to assume that Ranni found this and that it is the reason she took her own life and threw down her great rune. She is most likely to release herself from its influence and shatter the Elden Ring, freeing the other Shardbearers.
The Greater Will most certainly exploited the Shardbearers to gain power. For example, it most likely persuaded Radahn into halting the stars because other entities identical to it were attempting to enter the Lands Between. Astel, Naturalborn of the Void, who lives in the bottom levels of Nokstella, The Eternal City, suggests this. You’ll find Astel, Naturalbord of the void, by doing Renna’s Rise quest.
Ranni’s quest also hints that she requires the Fngerslaying blade from Nokron, The Eternal City, to free herself and continue her terrible path. She then hands you the inverted statue, which allows you to reach the top of the Carian tower, where her body resides. The ‘Cursemark of Death‘ is found on the body, and the flavor text hints that Ranni was the first Demigod to die. Killing not only herself but also the soul of ‘Prince of Death.’ When the two halves of the Cursemark of Death were combined, they murdered one complete Demigod. It murdered Ranni’s body but not her spirit. Which now dwells in the doll she inhabits, and it killed the soul but not the body of the Prince of Death. The Cursemark’s wording is as follows:
Cursemark carved into the discarded flesh of Ranni the Witch. She was also known as the half-wheel wound of the centipede.
This Cursemark was carved at the moment of Death of the first Demigod and should have taken the shape of a circle.
However, two demigods perished simultaneously, breaking the Cursemark into two half-wheels.
Ranni was the first of the demigods whose flesh perished, while the Prince of Death perished in the soul alone.
The Shattering began with the release of the ‘Prince of Death’. This shattering implies that Ranni sacrificed herself to shatter the Elden Ring, culminating in the Shattering. Her purpose is to bring an end to the Two Fingers and Greater Will that rule the Golden Order and usher in a new era. The Prince of Death was once known as Godwyn the Golden, as evidenced by the flavor text on the Prince of Death’s Pustule talisman, which reads:
A fetid pustule is taken from facial flesh Raises vitality. (Vitality governs resistance to the effects of Death.)
It is said that this blemish came from the visage of the Prince of Death, he who used to be called Godwyn. As First Dead of the demigods, it’s said he’s buried deep under the capital, at the Erdtree’s roots.
The player’s participation in her journey is assisting her success. At the end of her questline, it is suggested that she has slain the Two Fingers. Which is coincidentally about the same time that the ‘Two Fingers’ in the Roundtable Hold stop giving you ‘Advice’ and start ‘Consulting the Greater Will’ based on the level ranges for the gameplay involved with getting to the Erdtree and being denied by the thorns and
Perhaps Ranni intends to destroy the Golden Order and the Greater Will because she worships a different deity, one who takes the form of the Moon. Her previous life reinforces this as Lunar Princess Ranni of the Carian Royal Family. The Carian Royal Family invented Glintstone Sorcery, drawing its power directly from the power of the stars and MoonMoon before Radahn and the Golden Order detained the stars, thereby ending their influence on the earth. The Carian Royal Family and Caria are supposed to have existed before the Erdtree’s age, implying they were in the Lands Between before the Elden Ring was established and the Erdtree was founded. This thing would also explain why, after slaying the Elden Beast, the game’s lone ‘God,’ and calling Ranni, the big MoonMoon in the background that emerges transforms, exposing a black spiral-like mark within its face, she remarks:
“I do solemnly swear to every living being and every living soul. Now cometh the age of the stars. A thousand-year voyage under the wisdom of the MoonMoon. Here beginneth the chill night that encompasses all, reaching the great beyond. Into fear, doubt, and loneliness. As the path stretcheth into darkness. Well then, shall we? My fair consort, eternal.”
Sorcerer Sellen (Seluvis’s Rise Questline) suggests the stars and MoonMoon as another lifeform like the Erdtree (and respectively the Greater Will it represents) when you speak with her, and she tells you about Glintstone and says it is similar to Golden Amber. Which are some talismans suggest is Amber formed from the sap of the Erdtree. Sellen claims that the Amber retains vestiges of ancient life and houses its energy. She also claims that Glintstone is similar, except that the life contained is Residual life, the energy of the stars. Glintstone was developed before the formation of the Erdtree and represented the lingering influence of the stars and MoonMoon before the Golden Order’s ultimate rule.
Rennala (Mother of Ranni), Queen of Caria, and Radagon of the Golden Order married, putting an end to a war between the Erdtree and the MoonMoon. This implies that the Erdtree and thus the Golden Order once sought to destroy the house of the MoonMoon, most likely because the Greater Will sought to control the entire Lands Between. This hints that Ranni may strive to return her family and the gods they previously served to the position of authority they once held before the Erdtree’s formation when the Elden Beast fell to the planet.
After Godfrey, the First Elden Lord was exiled and became tarnished, Radagon left Rennala to become Queen Marika’s second husband and the Second Elden Lord.
I believe the ‘Age of Stars’ ending is the game’s ‘Good Ending,’ and not because of the memes about ‘love’ or whatever, but because the game’s lore suggests that the Golden Order, Erdtree, and the Greater Will are bad for the world and seek to control it through their influence over it and the power they control. Ranni initiated the Shattering to end the Greater Will’s power over the planet. Her questline is the player’s capacity to assist her in her endeavor to return the world to its pre-Golden Star state. A period when people derived power from stargazing rather than a few being awarded power by what appears to be an Old God of the Cosmos.