Yea, isn't my average CMC at 3.03? Is that the same as my mana curve?

I think that's a bit narrow to say "you don't want anything above 4 mana" at least generally. A midrange or control deck would usually have the more expensive cards as the end game. Your avg CMC is a bit high though. That is different.

RB discard aims on ending the game either with something like a 7/7 Nyxathid , The Rack for incremental damage. In the average competitive modern environment your Liliana Vess , Sire Of Insanity and Lord of the Void are going to be too expensive to make a real impact usually. Depending on the meta of course.

Stuff like Liliana's Caress and Megrim combined with Blightning and Burning Inquiry hits for big damage too.

jminute: Unless the card generates an immediate impact, is an answer or die card with something good, or provides continuous and constant advantage, 4 mana should be your limit for modern. Turn 4 is when the game tends to be decided.

Browbeat is just bad. They get to pick. Just play more Blightning and win. Liliana Vess is too slow, but her younger smaller sister is amazing. For R/B removal, make out Terminate. It hits most of the threats in the format.

I would personally focus the deck down. Run 12-16 creatures, the rest discard spells, lands and cards that benefit from discard.

Shall I show you what I might do with it?

Sure, at this point this deck really does what I want it to do and when I get the chance to play Liliana Vess or Lord of the Void I have plenty of mana at that point. I think Browbeat is fine for the purpose of this deck. Suppose I have a Chandra's Spitfire out on the field, then the opponent will probably let me draw three. Either way it plays out that card works for me. Having too much Blightning might not be worth it in the end when their hand size is already zero from all my other cards.

MindAblaze and LeaPlath, what do you think of the changes I've made?

Coming back to this after a few years and it's hilarious I was just learning about mana curve. Going to be slightly modifying this deck for a Modern clash event I'm doing just to see how it handles

I didn't do so great at the modern clash event at PAX East, quickly lost to my 2nd opponent's burn deck. On the bright side, each player I went up against gave me some tips, so I received more insight into how to improve this deck going forward.

I am considering adding some cards I recently played in Arena like Thoughtseize, Kroxa, Titan of Death's Hunger, Tinybones, Trinket Thief, Valki, God of Lies  ^Flip, Rankle, Master of Pranks, Tergrid, God of Fright  ^Flip along with a few others like Surgical Extraction.

I found that playing full playsets of fewer unique cards is more beneficial than playing 1-3 cards of more varied cards. I prefer making decks with as many different cards that can fit a theme, so I may create a different version of this deck in Commander which would allow that formulaic approach.

I was inspired to start playing paper formats again because of this event however, and will create a new Pioneer deck based on elements of this deck except in Grixis colors using cards like Drown in the Loch, Ashiok, Nightmare Muse and Nicol Bolas, the Ravager  ^Flip.

Overall, I had a great time playing this deck at PAX and definitely have to treat it with some fresh new sleeves!