The Ruins Greatsword is found by killing the Misbegotten Warrior and Crucible Knight boss duo at the Redmane Castle Plaza in Elden Ring. If you've been summoning phantoms or getting invaded by other players throughout the game, then you've probably seen plenty of people sporting this extremely powerful weapon.
As if this massive sword, or rather stone slab, didn't have enough range to begin with, it's also capable of launching a deadly long-range magic attack by using its unique Ashes of War. This guide will explain how you can cause the boss duo to spawn so you can defeat them and claim your new colossal sword.
Updated by Hamza Haq on October 20, 2023: New images have been added to the article to give players a better visual clue on how to trigger the boss fight to obtain the Ruins Greatsword. We've also added a tip on how to get the Greatsword before fighting Radhan.
Redmane Castle Plaza
Redmane Castle can be found in the southeastern corner of Caelid, located on the far side of a bridge. When you enter Redmane Castle for the first time, you may not encounter the Misbegotten Warrior and Crucible Knight boss fight.
Depending on whether or not you've already triggered the Radahn Festival, you may see a handful of friendly NPCs standing around in the location where the boss fight is supposed to be. If this is the case, don't worry because you can still get the Ruins Greatsword later on after you defeat General Radahn.
Radahn Festival
The Radahn Festival begins after you either progress far enough through Ranni's questline that she sends you out to kill Radahn, or after you reach the Altus Plateau and interact with any site of grace in that area.
If you reach the Redmane Castle Plaza and you see Warrior Jar Alexander, Blaidd the Half-Wolf, and a few other NPCs all waiting around and talking about their plans to take down Radahn, then you'll know you've already begun the festival and you'll need to go ahead and fight Radahn. Luckily, you'll have the help of all the NPCs in the plaza, as well as any phantoms you summon.
After you've defeated Radahn, you need to return to the building between the plaza and the lift that takes you down to the teleporter for Radahn's boss arena. Once you're in the building, simply speak to Witch-Hunter Jerren one last time and exhaust all his dialogue, then return to the nearby Chamber Outside the Plaza Site of Grace and rest at it.
After you've taken these steps, you can go back to the plaza where you will now have the chance to fight the Misbegotten Warrior and Crucible Knight bosses.
You don't need to defeat Radhan to obtain the Ruins Greatsword. If you don't activate the Lift and get to Redmane early, you can trigger the boss fight in the Plaza to get the Greatsword.
The Boss Fight
Whether you already beat Radahn or you reached the castle before ever starting the festival, your main objective at this point should be taking down the boss duo in the Redmane Castle Plaza. It can be quite tricky fending off both bosses simultaneously, so it's ideal to utilize either your most powerful spirit ashes or the help of a friendly phantom.
It is recommended to try and kill the Misbegotten Warrior first, as he is far more aggressive and dangerous than the Crucible Knight. If you backpedal enough you can keep the Crucible Knight at a distance while you fight the Misbegotten Warrior, but the Misbegotten Warrior will keep charging you and launching vicious attacks until he's dead.
After you've vanquished the deadly duo, they'll instantly drop the Ruins Greatsword and you can continue your adventures through the Lands Between while wielding your brand new magical, deadly, massive stone sword.