Umbris, Fear Manifest + Opposition Agent + Hive Mind + Mana Severance + Chainer, Dementia Master

Umbris, Fear Manifest

Opposition Agent

Hive Mind

Mana Severance

Chainer, Dementia Master

How it works

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

This elegant loop turns a seemingly simple land-removal spell into a total library wipe, fueled by Hive Mind forcing your opponents to cast Mana Severance alongside you. Once their lands are completely gone, Opposition Agent ensures that any subsequent search effects would also clean out whatever remains, though you won't even need it once Chainer, Dementia Master gets to work. By repeatedly reanimating creatures under Chainer's command, you trigger Umbris, Fear Manifest over and over; because your opponents have no lands left in their libraries to stop the process, Umbris simply devours the rest of their decks in one massive sweep while growing to a terrifyingly vast size.