It occurs often when Fayne's [Decrease Def] and [Weaken] lands on Spider20, one of the debuffs I mentioned does not activate. I am not sure which doesn't activate, but what I am 300% sure is that one of each does not activate on the Spider since I "always" done it in 30 secs but sometimes I failed  on Spider20. PLZ check if there's a problem. Thx