Umori, the Collector plus some of the other new tools from Ikoria push Mono Black Devotion in Standard to an entirely new level.
Umori Mono Black Devotion Decklist (Standard)
1 Umori, the Collector 1 Ayara, First of Locthwain 4 Gutterbones 3 Midnight Reaper 4 Priest of Forgotten Gods 4 Lazotep Reaver 3 Murderous Rider/Swift End 3 Gray Merchant of Asphodel 4 Whisper Squad 3 Nightmare Shepherd 2 Woe Strider 4 Fiend Artisan 2 Lurrus of the Dream Den 4 Castle Locthwain 19 Swamp (339)
At face value Umori does have a more real deckbuilding restriction than some of the others, since we're only able to run creatures. This means no cards like Witch's Oven or Command the Dreadhorde or random instant-speed removal. However, if you look at Mono Black Devotion decklists from the past, they're mostly just running creatures anyway! We still have an embarassment of riches to choose from when it comes to black creatures in Standard. The payoff is huge – we get access to an extra card in our hand every single game – a very castable efficiently sized creature that serves as a Jet Medallion for our entire deck that is looking to dump as many creatures onto the battlefield as possible. It even has two mana symbols for devotion!
Gray Merchant is still the main reason to build a mono black devotion deck in the first place, but Fiend Artisan gives us a huge boost. Previous builds of this archetype were playing some subpar 2-drops that just happened to have two black mana symbols but that wouldn't really be seeing play in other archetypes. Fiend Artisan, on the other hand, has a power level off the charts and is seeing play in a wide variety of decklists. It fits perfectly here, letting us tutor out key creatures and increasing the likelihood of our combo kill.
As usual, the 3-drop slot for these black-based decks is glutted, but due to Fiend Artisan we likely want to include at least one copy of each in the final decklist. Lurrus is an exciting new option that seems great since it can bring back powerhouses like Fiend Artisan or Priest of Forgotten Gods and still serves as a lightning rod for a removal spell. Murderous Rider is noteworthy since it lets us still play a premium interactive spell within the confines of Umori's deckbuilding restriction.
Check out this video of us enjoying casting Umori on turn 4 every game: