Organic Extinction

Improvise (Your artifacts can help cast this spell. Each artifact you tap after you're done activating mana abilities pays for {1}.)
Destroy all nonartifact creatures.

Absolute Virtue

This spell can't be countered.
Flying
You have protection from each of your opponents. (You can't be dealt damage, enchanted, or targeted by anything controlled by your opponents.)

Conjurer's Closet

At the beginning of your end step, you may exile target creature you control, then return that card to the battlefield under your control.

Sothera, the Supervoid

Whenever a creature you control dies, each opponent chooses a creature they control and exiles it.
At the beginning of your end step, if a player controls no creatures, sacrifice Sothera, then put a creature card exiled with it onto the battlefield under your control with two additional +1/+1 counters on it.

Singularity Rupture

Destroy all creatures, then any number of target players each mill half their library, rounded down.