Ranni the Witch's quest is one of the most complex in Elden Ring, containing hours of content, lore, and an alternate ending to the game. Although its intricate steps, multiple bosses, and length can put off some players, there are plenty of benefits to playing through the entire thing.
One big bonus is getting the Dark Moon Greatsword, which is one of the better weapons in the game alongside the Sword of Night and Flame. There are plenty of other items to collect throughout the quest as well, like the Snow Witch Armor Set and the Remembrance of the Naturalborn. A good amount of lore is uncovered throughout the quest as well, so it's a necessity for any player who wants to get into the finer details of Elden Ring's story. It also answers the question of the chest in the Grand Library of Raya Lucaria, which cannot be opened without playing through almost the entire mission.
The first time players see Ranni is in the Church of Elleh in Limgrave, where she goes by Renna and gives the Spirit Calling Bell and Lone Wolf Ashes. After this, she's absent until reaching Three Sisters after defeating the Royal Knight Loretta. Three Sisters contains three wizard towers: Renna's Rise, Ranni's Rise and Seluvis' Rise. First, the player should head into Ranni's Rise and speak with Ranni, who asks you to talk to War Counselor Iji, Preceptor Seluvis and Blaidd, who are all on the ground floor. Ranni then says to find Nokron City with Blaidd.
The player should then go to East Limgrave, find the Siofra River Well, and use the lift inside of it. This leads to the Siofra River area, where the player should head northeast until they find Blaidd, who says to speak with Seluvis. After going back to Three Sisters, Seluvis gives the item Seluvis' Introduction and tells the player to find Sorceress Sellen in Limgrave. She's at the Ruins Cellar Site of Grace and instructs the gamer to defeat General Radahn in order to get into Nokron. After talking with her, head back to Blaidd, who says Radahn will be at a festival in Caelid.
After reaching Caelid, go to the Impassible Greatbridge Site of Grace, which has a waygate into Redmane Castle. Once inside, the player can tell the Festival Master that they're ready. The waypoint on the other side of the castle leads to the Wailing Dunes, which is where Radahn is. Since his fight is one of the hardest in the game, looking through a guide is recommended. Afterward, a star will drop in Limgrave and open an entrance to Nokron. Speak to Blaidd at the Scarscourge Radahn Site of Grace. He says to meet him where the star fell, but he isn't there. If the player asks War Counselor Iji, located at the Road to Manor Site of Grace, he says not to worry. The player can go to the Forlorn Hound Evergoal, perform the Finger Snap Gesture to speak with Blaidd, and open the evergaol to free him.
After heading back to Limgrave, drop into the crater and use the ledges to descend onto the rooftops of Nokron. Head southeast from the Nokron, Eternal City Site of Grace, until a Mimic Tear is found, and a fight ensues. It mimics the player's equipment at the beginning of the fight, so unequip everything and put it back on after the fight starts to put the Mimic at a disadvantage. After defeating it, continue to the Eternal Woods and then drop into the Night's Sacred Ground area. Heading north from the Site of Grace, a chest will eventually be found with the Fingerslayer Blade in it, which is what Ranni wanted.
After speaking with Ranni back in her tower, she relinquishes the Carian Inverted Statue, which can eventually open a secret area in the Carian Study Hall, the player's next destination. After examining the pedestal in the main hall, use the elevator shaft to go to the lower floor and fight Preceptor Miriam. Then, go through the door leading to the Liurnia Tower Bridge Site of Grace. After fighting a Godskin Noble on the bridge, continue to the Divine Tower of Liurnia and take the elevator to the top, where there's a corpse with the Cursemark of Death and Stargazer Heirloom. Rather than going through the process of respec-ing a character, players can use the Stargazer Heirloom to increase their Intelligence by five.
Upon returning to Ranni's Rise, the player will find Ranni absent. Head to Renna's Rise to find the Snow Witch armor set. Funnily enough, the hat is the only part of the set to strengthen Frost sorcery, and it does so by 10%. After getting the set, use the Waygate to teleport to Ansel River Main, right by a corpse that's holding a Miniature Ranni doll. Go south to the Ansel Main River Site of Grace and attempt to talk to the miniature Ranni. After trying a few times, she says to defeat the Baleful Shadow, which is at the end of the southern tunnel in the Nokstella River Basin. It drops a Discarded Palace Key, which is used to unlock the chest in the Grand Library of Raya Lucaria after defeating Rennala, Queen of the Full Moon. Inside the chest is the Dark Moon Ring.
Continue south, enter the building, and take the lift to the Lake of Rot. Use the buttons to make it across the lake and then travel along the river. Eventually, there's a coffin, and resting in it takes the player to Astel, Naturalborn of the Void's boss fight. The Dark Moon Ring is required to enter this area. Defeating Ansel yields the Remembrance of the Naturalborn, which can be sold for 30,000 Runes or traded to Enia for either Ash of War: Waves of Darkness or the Bastard's Stars. Take the Deep Ansel Well up to the Moonlight Altar. After defeating Glintstone Dragon Adula, go to the Cathedral of Manus Celes and drop down to the cave south of the Site of Grace. Following the tunnel leads the player to Ranni's and a Two Finger's corpse. The player is prompted to wear the ring and can then grab the Dark Moon Greatsword.
The Dark Moon Greatsword scales with Intelligence, Dexterity and Strength. Its skill, Moonlight Greatsword, increases its magic attack power and applies a Frost stat. It also comes with a charge attack that shoots a beam of moonlight at enemies, dealing a pretty good chunk of damage. The Greatsword is best with the Astrologer class, and generally speaking, builds including it will max Mind and Intelligence. The Snow Witch Armor set from earlier on in the quest works great with it, along with Godfrey's Icon and the Shard of Alexander.
The Dark Moon Greatsword's primary weakness is its low damage and speed. While it can easily stagger and Frost bosses, its slow fire speed leaves some players feeling vulnerable when using it. The animation for the buff is also pretty slow, which can leave players in a bad spot. Overall, whether the weapon is good or not heavily depends on the player's build and playstyle.