Cast Conflux, searching your library for a white card, blue card, black card, red card, and green card in your library that together do not share a mana value with each other or at least one of the additional cards in your hand.
Attack an opponent who is unable to block Atemsis with Atemsis.
On damage, Atemsis triggers, allowing you to reveal your hand and losing that player the game.

Target opponent loses the game

Atemsis, All-Seeing

Conflux

Declare Atemsis as an attacker.
Atemsis' myriad ability triggers, creating a token copy of Atemsis tapped and attacking each other opponent.
Deal combat damage using each Atemsis, triggering their abilities.
Resolve each Atemsis trigger, causing you to reveal your hand and causing each opponent to lose the game.

Each opponent loses the game

Blade of Selves

Mirror Box

Sakashima of a Thousand Faces

Cast Artful Dodge by paying {U}, targeting Atemsis.
Atemsis triggers, dealing 2 damage to an opponent.
Atemsis triggers, causing you to reveal your hand, and causing the damaged opponent to lose the game.
Resolve Artful Dodge, causing Atemsis to be unblockable this turn.
If you have one opponent remaining, skip to step 9.
Otherwise, cast Artful Dodge from your graveyard for its flashback cost by paying {U}, targeting Atemsis.
Repeat steps 2 and 3 one additional time.
Resolve Artful Dodge, exiling it.
Deal combat damage to the remaining opponent using Atemsis.
Atemsis triggers, causing you to reveal your hand, and causing the damaged opponent to lose the game.


Livewire Lash

Artful Dodge

Cast Diabolic Revelation by paying at most {9}{B}{B}, searching your library for at most six cards with differing mana values and putting them into your hand.
Move to your combat phase, and deal combat damage to an opponent with Atemsis.
Atemsis triggers, revealing your hand and causing the opponent dealt combat damage to lose the game.

Diabolic Revelation

Cast the noncreature card by paying its mana cost.
Atemsis triggers, dealing 1 damage to each opponent.
Atemsis triggers once per opponent, revealing your hand and causing each opponent to lose the game.

Black Mage's Rod

Mirror Gallery

Cast Weird Harvest by paying at most {6}{G}{G}, searching your library for at most six creature cards with differing mana values, putting them into your hand, and allowing each opponent to do the same.
Move to your combat phase, and deal combat damage to an opponent with Atemsis.
Atemsis triggers, revealing your hand and causing the opponent dealt combat damage to lose the game.

Combos with "Atemsis, All-Seeing"