It is worth noting that the spell Holy is perhaps the only spell effect that still has a visual, even if the target was Silenced.
Seeing that I've hacked the game a little to remove the boss bit, it becomes apparent.
It isn't like Flare/Nuke where it fails to be cast and you get no visual at all
(although that spell is one of the other few that has a strange effect of seeing some red flashes in the background, even if it misses its target).