Radagon’s Soreseal is found in a rather conspicuous location, but first, you must make your way to the Fort Faroth Site of Grace in Caelid. From there, make your way into the fort and climb up the stairs, ignoring the oversized harpies and bats. Once at the top, jump off to the right on the huge platform – ignore all the enemies here and jump into the second hole towards the top right. Run forward, and you’ll notice another platform you can jump to, behind you on the right. That’s where you’ll find the Radagon’s Soreseal, which will be guarded by two small and one giant rat.