Overall, I'm confused about what this deck sets out to accomplish, It's not a tribal deck, and it's not really artifact focused either... It seems like it'd be discard, but that doesn't seem to have a lot of presence either, since you could easily use Things like Library of Leng, force all people to discard cards, and take advantage of the fact that you get your cards back, as well as the fact that you don't have any enchantments that cause any/all cards that would hit a graveyard to be exiled instead.

Overall, I don't really see a "Focus" for the deck. If you're going rakdos hellbent, you'd want far easier ways for you to discard your hand, and use flashback and hellbent effects in concert so as to be able to really take advantage of any discard you yourself might suffer.

Actually, come to think about it, Library of Leng is probably the absolute BEST possible card for your deck.

Essentially its about playing hellbent with a lot of card draw but playing hellbent with immediate access to cards to cast that arent actually in hand, while damaging opponents with loss of life effects doing most of the damage. Keep their creature count low and have them discard a lot. With olivia I can ping critters to build her up quick or take control of their creatures. By keeping their critter count low, I can even turn a land into a creature and pump it up to attack with if needed. Mirage Mirror lets me copy enchamtments so i can double effects of them, or copy someone elses creature or artifact, etc.

Bonus card draw bonuses stack while playing hellbent and I can be hellbent with access to cards still using Uba Mask or Ice Cauldron.

So control the board while paper cutting opponents, with ability to hit hard a few ways too. That's the end goal. Library of leng is not really a good fit.

Why not run the Rings of Brighthearth + Basalt Monolith combo, since you run Exsanguinate.