Alright, a lot of people are going to tell you "don't run this." And I'm going to be one of those people and advise that, competitively, you're going to want to be basically all aggro without the cute discard theme.
That being said -- I'll workshop this for some kind of standard discard hybrid thing, because I have a soft spot for old timey discard decks.
Things you should look into that will help your discard theme:
- Liliana of the Veil
- Rakdos's Return
- Gruesome Discovery
and a full set of your Shrieking Affliction
And you'll probably want to do something with all those cards your opponent discarded though, you know, as a contingency plan... look into a couple Grimoire of the Dead
So like I said, those are some options. The deck could be cute, but probably won't do a heck of a lot besides make your opponent irritated while top decking. Look into some of the Rakdos Aggro threads for more competitive Rakdos builds if you're interested.