We've seen a variety of Death's Shadow decks pop up in Modern from time to time. In the past they've largely been hyperaggressive Zoo variants or Grixis flavors that involve other elements like Kiln Fiend as a complement to Death's Shadow.
TheLousyZoot has truly embraced Death's Shadow as a combo deck. This mostly B/W version is more-or-less all-in on Death's Shadow as a win condition. Angel's Grace and Phyrexian Unlife are largely associated with Ad Nauseam in Modern, but this deck makes great use of them.
Not only do these cards simply allow Death's Shadow to "race" opposition at dangerously low life totals, but in conjunction with Plunge into Darkness and Spoils of the Vault, it is elementary to set up a lethal Death's Shadow in combination with a protection spell. You can even instantly kill your opponent with Rite of Consumption outside the combat step!
With all the redundant means to find Death's Shadows, Hex Parasite is the best option for powering up the black one-drop. It can grow our win condition at an unparalleled rate and even has a few backdoor applications throughout Modern as a disruptive creature.
Orzhov Charm is one of my favorite cards in this decklist. Not only does it serve as a removal spell in a pinch that shaves your life total as necessary to set up Death's Shadow, it can even rebuy Death's Shadow or Hex Parasite!
The sideboard uses some of the usual suspects of hate cards in Modern, but it does notably eschew Stony Silence. The really spicy one here is Not of This World. Death's Shadow is all about incinerating its life total, and Not of This World is functionally a free counterspell in highly interactive matchups that should blindside opponents.
I'm a huge fan of all the interesting design decisions that have been made to produce this new take on an old combo deck. It's unique and looks both resilient and powerful. My hat's off to you, TheLousyZoot!