That is my main commune prior to demonfire. And even with demonfire I liked fatigue cause it costed less. Sure fatigue straight up is the best way in certain cases. But choosing that also killed me against Kargthak. You have to know when to use it and when to use other communes to ensure you get the kill. Running spamming fatigue will likely make a lot of people teleport. Some instances it is a risk worth taking.
Knowing when to blind/plague/fatigue and NOT SCARE your opponent to quaff right away/stick around long enough is very important. I cant name how many battles I scared my enemy too quick and it left me with wasted time and cocky tells coming at me calling me "weak" "pathetic" "hahahah you suck"