She is most notable for being the primary catalyst to the events of Elden Ring, and the instigator of one of the game's main quest lines, culminating in the hidden "Age of Stars" ending in which the player character becomes her royal consort.

Her doll appearance has light-blue skin, medium-length hair, and even lighter, snow-colored clothing, with a large witch hat, a fur cloak, four arms, and a spectral second face alongside her own.

Prior to the game's events, Ranni was born to second Elden Lord Radagon and Queen Rennala of Caria, whose marriage prompted an alliance between the opposing forces of the Golden Order, who served the Greater Will, and the Carian nobles, who drew magical powers from the cosmos.

Ranni used the other half of the stolen rune to kill her physical body and escape the control of the Greater Will, binding her soul to a doll modeled after her mentor, the ice witch Renna.

[5] The player must then defeat the demigod General Radahn to gain access to Nokron, the Eternal City, and obtain the Fingerslayer Blade, a weapon capable of slaying the Two Fingers, servants of the Greater Will.

[6] The player may choose to summon Ranni immediately prior to the ending, prompting the Elden Ring's destruction and the start of the Age of Stars, a "thousand-year period of darkness and fear".

[9] Ian Walker of Kotaku speculated that Ranni's character was inspired by the young witch Schierke from Berserk, a manga that has commonly influenced the works of Hidetaka Miyazaki.

[10] A Famitsu survey resulted in Ranni as the character who left the strongest impression on players, with her guardian Blaidd also ranking third beneath Iron Fist Alexander.

Calling Ranni a "hero" despite her "self-serving" mission, he noted that her abandonment of Blaidd could be construed as personal sacrifice rather than a cruel move, and that she is ultimately putting the needs of others before her own, due to her belief that gods should not interfere in the lives of mortals.

[11] In 2023, YouTuber VaatiVidya was noted by PC Gamer as having created a fan animation, An Elden Ring Movie: Age of the Stars, depicting a more linear illustrated narrative of Ranni and Blaidd's backstory based on collected in-game lore.