The Lost Caverns of Ixalan

Instant

As an additional cost to cast this spell, discard a card or pay 3 life.
Destroy target creature or planeswalker.

Bitter Triumph

Task master

LGLD

This is the actual decklist that I own.
Draft the Commanders first from a special pool (in the sideboard) with 4 packs of 10 or 12.
Each commander has partner. If you want to use one of the companions, you can do that as well if you abide by the companion rules and color identity rules. For Umori specifically, you may still have creatures as your commanders as long as the rest of the deck follows its companion rules.
I suggest choosing your commanders (and sometimes a companion) before you've drafted from the main pool. 
Each player automatically gets a command tower and an arcane signet.
Before drafting, players can decide if they want to draft 60 card commander decks or full-sized 100 card decks.
Draft 4 packs of 14 for 60 card decks and 6 or 7 packs of 14 for 100 card decks.
Color Identity does not matter when it comes to lands.
Draft Archetypes:
Reanimator
Cast spell, get value
Freecasting
Theft
Copying spells
Value for targeting your own creatures

(The Real) Budget Spellslinger Commander Cube

Double Toxic

Tribal Orc and Goblin with Treasure Token Ramp

Orc and Goblin Treasure Hunters

Dimir Excruciator (Copy)

Dimir Excruciator

Strain Bravo: [Neuropathic pain] 
​Virulence: 8.5/10
​Pathology: A highly oppressive, symmetrical punisher. This strain attacks the host's central nervous system, turning their natural survival instincts against them. When the host attempts to draw cards, tap mana, or cast efficient spells, the pathogen triggers agonizing feedback loops (Roiling Vortex, Manabarbs, Spellshock).

Bitter Triumph

Rules Text

Card Facts

Legality

Rulings

Every version

Decks using this card