Elden Ring's vast map contains a plethora of bosses. The majority of them are extremely difficult to defeat, while others require little to no effort. The Cleanrot Knight is one of the game's bosses, and he's not too difficult to defeat. However, in order to find this boss, you must first locate Stillwater Cave.
It is actually quite simple to get to the cave; first, you must visit Liurna of the Lakes' Site of Grace. After that, proceed southeast until you reach the cliffs. Continue on until you reach Stillwater Cave, which has a Site of Grace sitting beside the cave.
As with any other cave, once you enter, you may find message appraisals written by other players to assist or warn you with your exploration. Inside the cave, there will be a lot of poison, so be cautious. There will also be flowers in the cave that will release more poison, so the best option is to simply run straight ahead without pausing.
When you reach the mist, rest for a while to allow the poison to wear off. Enter the mist and prepare for the fight after you've rested for a while.
The Cleanrot Knight, armed with a sword and a spear, will be encountered. It has a number of attacks and skills to be aware of, such as the ability to spit acid-like liquid that deals a lot of damage when it lands on you. It can also cause dangerous spikes of holy spears to emerge from the ground, so use caution.
The Cleanrot Knight has a charged attack in which it attempts to thrust its spear at you. However, if you are hit, you will be affected by a debuff called Scarlet Rot. This debuff will continuously degrade your health throughout the fight, making it extremely dangerous.
Long-ranged attacks are one way to easily fell this boss. Close-ranged melee attacks against it will be much more difficult if your gear isn't yet that high-level.
Once the fight begins, you can summon Ash Lone Wolves, which are excellent for distracting any type of boss. Once the boss is preoccupied by the wolves, you can now use long-ranged attacks to inflict damage on its health. High-level spells are recommended because some of them, such as Loretta's Greatbow, deal massive damage.