[Autumn]

As far as I know, Divine Shower shouldn't proc on defeat effects 6 times. Which ones are being triggered?

Also, does this not work for most of the skills in the game, being able to target defeated enemies?

You can target them but inflictions usually do not get put onto corpses, this was specifically a change some manner of years back. But unfortunately I cannot for the life of me find those patch notes, either way I am not miffed if this interaction is kept in, figured it might be unintended behavior since you usually can't apply effects to corpses.