Cast Ruthless Technomancer by paying {3}{B}.
Ruthless Technomancer enters the battlefield, causing you to sacrifice Umbris and create at least seven Treasure tokens.
Activate six Treasure tokens by tapping and sacrificing them, adding {4}{B}{B}.
Activate Ruthless Technomancer by paying {2}{B} and sacrifcing Phyrexian Metamorph, returning Umbris from your graveyard to the battlefield.
Umbris enters the battlefield, causing target opponent to exile cards from the top of your library until they exile a land card.
Activate Ruthless Technomancer by paying {2}{B} and sacrifcing a Treasure token, returning Phyrexian Metamorph from your graveyard to the battlefield as a copy of Ruthless Technomancer.
Phyrexian Metamorph enters the battlefield, causing you to sacrifice Umbris and create at least seven Treasure tokens.
Repeat from step 3.

Exile each opponent's library

Infinite colored mana

Infinite death triggers

Infinite ETB

Infinite LTB

Infinite sacrifice triggers

Infinite Treasure tokens

Return all creature cards from your graveyard to the battlefield

Umbris, Fear Manifest

Ruthless Technomancer

Phyrexian Metamorph

Cast Ruthless Technomancer by paying {3}{B}.
Ruthless Technomancer enters the battlefield, causing you to sacrifice Umbris and create at least seven Treasure tokens.
Activate six Treasure tokens by tapping and sacrificing them, adding {4}{B}{B}.
Activate Ruthless Technomancer by paying {2}{B} and sacrifcing Auton Soldier, returning Umbris from your graveyard to the battlefield.
Umbris enters the battlefield, causing target opponent to exile cards from the top of your library until they exile a land card.
Activate Ruthless Technomancer by paying {2}{B} and sacrifcing a Treasure token, returning Auton Soldier from your graveyard to the battlefield as a copy of Ruthless Technomancer.
Auton Soldier enters the battlefield, causing you to sacrifice Umbris and create at least seven Treasure tokens.
Repeat from step 3.

Auton Soldier

Cast Mana Severance by paying {1}{U}.
Hive Mind triggers, causing each opponent to copy Mana Severance.
Resolve each opponent's Mana Severance, searching for and exiling all land cards from their libraries.
Resolve your Mana Severance, choosing not to exile any land cards from your library.
Move to your combat step.
Attack with Umbris.
Umbris triggers, creating a token copy of Umbris for each opponent you have, with each token tapped and attacking a different opponent.
Put all but one Umbris into your graveyard due to the legend rule.
Umbris triggers for each Umbris token that enters and each Umbris token triggers for itself and each other Umbris that enters.
Resolve the Umbris triggers, revealing no lands from opponent libraries and exiling each opponent library.

Near-infinitely large Umbris

Opposition Agent

Hive Mind

Mana Severance

Blade of Selves

Cast Mana Severance by paying {1}{U}.
Hive Mind triggers, causing each opponent to copy Mana Severance.
Resolve each opponent's Mana Severance, searching for and exiling all land cards from their libraries.
Resolve your Mana Severance, choosing not to exile any land cards from your library.
Activate Umbris by paying {1}{U}, blinking Umbris.
Umbris triggers, revealing no lands from an opponent library, exiling their library.
Repeat from step 5 for each opponent.

Deadeye Navigator

Cast Mana Severance by paying {1}{U}.
Hive Mind triggers, causing each opponent to copy Mana Severance.
Resolve each opponent's Mana Severance, searching for and exiling all land cards from their libraries.
Resolve your Mana Severance, choosing not to exile any land cards from your library.
Activate Chainer by paying {B}{B}{B} and three life, returning a creature card from your graveyard to the battlefield as a black Nightmare in addition to its other creature types.
That creature enters the battlefield, triggering Umbris.
Resolve the Umbris trigger, revealing no lands from an opponent library, exiling their library.
Repeat from step 5 for each opponent.

Combos with "Umbris, Fear Manifest"