Could you describe "Legendary", the Guardians themselves can't be tamed, the 2 Endbosses, Alduin and Alani can be tamed, for doing so you will need to craft their correct Matrix and Knocking them out isnt required since you feed this Matrix passively!
Making either of the Matrix requires having killed each Guardian atleast a couple of times.

Hopefully you can work it out like so,

Scrimshaws

@Scrimshaws I fiddled with your mod and figured it out, thanks for respond though!