Is 80 Atk/Str/Def with karils high enough level to take on Waterfiends? If not, what is the lowest level combat stats needed to successfully fight them?

That is alright I suppose, I really dont recommend them till 90+'s unless you are on slayer task but other people think that at flat 80's you can do it.

I would say that at least 90+ SOMETHING (att, str or def, probably att or def being the best one) would give you a distinct advantage. I was killing them rather easily with 99 def, 94 att and 80 str. But then again I was on a slayer task.

 

 

 

I'd go for at least 85 in all before going. I think that is the bare minimum for being able to kill them effectively.