Radaggan is not a bad set but a clunky one due to lack of % speed. I had an idea of Radaggan Deceiver with Acid Purge quite some time ago, but needless to say I scraped it because of 0% casting speed.
I made a Cabalist just a couple of days ago, and while it plays rather nicely, it still suffers of low (~128%) casting speed. It has 2 skills on low cooldown and 2 debuffs which you need to cast constanlty.
I’m surprised no one suggested Radaggan to receive some % total speed or at least some % CS.