While this won’t be the first time you encounter a Cleanrot Knight boss if you’ve been through Liurnia of the Lakes, this time, you will have to fight two of them at once, which sounds more complicated than it actually is.
The bosses can be backstabbed and staggered
Summons can consistently keep the bosses staggered
Physical attacks are easy to block
The strategy for this fight is rather simple, and revolves around the use of the Lone Wolf Ashes. With both of these bosses being very vulnerable to being staggered, summoning these wolves at the start of the fight will help you greatly in dealing with the spear wielding Cleanrot Knight. The boss will get staggered by each of your wolves’ attacks, with one exception, when he’s blocking by crossing his weapons. With that in mind, summon your wolves as soon as you enter the boss room, and you will have two different ways of approaching this fight:
If you’re playing ranged, you can simply keep walking backwards while using spells/ranged attacks, and your wolves will do a good enough job of keeping the boss busy for you to be mostly safe.
If you’re melee, you can keep using jumping heavy attacks while your wolves distract and stagger the boss. Doing so will not only break the boss’s stance and leave him vulnerable to a critical attack, but will also keep staggering him and interrupting most of his attempts to retaliate. There is however one thing to watch out for: the boss blocking by crossing his weapons. While you will still be able to inflict damage, the boss won’t be staggered, and will retaliate with a shove followed by a deadly Impale attack that cannot be blocked.
You can either dodge it with a well timed roll, or avoid it altogether by dodging the shove and not leaving the boss any breathing room. While the boss will still sometimes use this attack separately, dodging as shown above, remaining aggressive and staggering the boss, or simply outranging the boss will make this attack a non-issue.
As for the sickle wielding boss, you will be able to ignore him for the most part while you’re dealing with the spear wielding one. While he will be slowly walking towards you while using a ranged attack that throws up to two discs towards you, those can be avoided by rolling towards each of the discs. Just make sure to either stand in a way that will allow you to see both Cleanrot Knights at all times, or turn up your sound to hear the discs being thrown out.
Once the spear wielding boss is dead, the remaining one will be much easier to deal with. If you’re ranged, you’ll just have to worry about the ranged attack, while if you’re melee, you won’t have to worry about being blocked or Impaled anymore, and you can just continuously use jumping heavy attacks to stagger the boss and break his stance. The boss will sometimes retaliate with a quick melee attack, which you can either block by raising your shield after each of your jumping heavy attacks, rolling after a jumping heavy attack, or simply tanking it if you have enough health/flasks.