So 8 rack has always been a strategy that has intrigued me in Modern. When Pioneer officially dropped as a format, I realized I had both Shrieking Affliction and Davriel, Rogue Shadowmage to my disposal for building an 8 Rack type deck.
The decks main discard package relies on Thoughtseize to hit our opponent on turn 1. A new addition from Theros, Beyond Death is Kroxa, Titan of Death's Hunger, mainly because its a two man discard spell that can drain and we can usually bring him back reliably. We also have a full set of Collective Brutality to act as both discard and removal or burn. Additionally, Kolaghan's Command is there for the same reason as well as artifact hate. Rakdos's Return is to top off our discard and to put our opponents empty handed. Davriel, Rogue Shadowmage and Angrath, the Flame-Chained help keep our opponents hand empty while maintaining consistent, heavy damage, especially with the combination of Shrieking Affliction.
The rest of the deck offers a basic removal shell. A full set of Dreadbore helps deal with both creatures and planeswalkers. We also have our Collective Brutalitys and Kolaghan's Command to deal with smaller threats. Additionally, Sign in Blood is in the deck to dig for gas and help maintain card advantage over our opponent.
The Rogue Deckbuilder has some similar 8 rack brews and I would highly recommend checking them out.
https://www.youtube.com/watch?v=ARKSmo3xlAg&t=324s
The large difference between his list and my list is creatures. The Rogue Deckbuilder plays cards like Yarok's Fenlurkers and Plaguecrafters. Although I see why someone would use these in a discard strategy, (creatures which discard cards and get in for damage), I don't necessarily think they're that great. The largest Yarok's Fenlurker will get is 2 or 3 power and Plaguecrafter doesn't do a great job with removing important threats. Sacrifice leaves your opponent with the choice of which creature to kill, and the Plaguecrafter usually gets sacrificed to himself and is conditionally just a 3 mana discard spell.
I also think it's worth mentioning that with my deck running no creatures, I leave my opponent's removal dead. I can prioritize there important "GAS" cards to be discarded while leaving removal in their hand to be discarded by Kroxa, Titan of Death's Hunger or Davriel, Rogue Shadowmage.
Sideboard is straightforward enough. Duress to deal with any control or phoenix matchups. Slaughter Games takes care of combo decks like Sylvan Awakening and Jeskai Ascendancy. Leyline of the Void bombs any graveyard-based strategies such as dredge or phoenix. Bontu's Last Reckoning takes care of any creature-based strategies. Alpine Moon shuts down Field of the Dead or any extra-mana lands like Nykthos, Shrine to Nyx.
