Breach the Multiverse + Umbral Collar Zealot + Dualcaster Mage
Breach the Multiverse
Umbral Collar Zealot
Dualcaster Mage
Infinite creature LTBInfinite creature ETBInfinite creature sacrifice triggersInfinite death triggersInfinite millInfinite self-millPut all creature cards from your library onto the battlefieldInfinite magecraft triggersInfinite surveilInfinite recursion of creature cards in your graveyardPut all creature cards from each opponent's library onto the battlefield under your control
How it works
Cast Breach the Multiverse by paying its mana cost, targeting any applicable target.
Holding priority, cast Dualcaster Mage by paying its mana cost.
When Dualcaster Mage enters, it triggers, targeting Breach the Multiverse.
Holding priority, activate Umbral Collar Zealot by sacrificing Dualcaster Mage.
Resolve the Dualcaster Mage trigger, copying Breach the Multiverse, with the copy targeting Dualcaster Mage
Resolve the Breach the Multiverse copy, returning Dualcaster Mage from your graveyard to the battlefield.
Repeat from step 3.
By casting Breach the Multiverse and holding priority to drop Dualcaster Mage, you set up an infinite feedback loop where the Mage's enters-the-battlefield ability perpetually copies the original sorcery. Before that copy resolves, you use Umbral Collar Zealot to sacrifice Dualcaster Mage, putting it into the graveyard just in time for the resolving copy of Breach the Multiverse to resurrect it. This cycle repeats endlessly, milling everyone out, draining libraries of their best creatures directly onto your board, and leveraging the Zealot's sacrifice outlet to dig through your entire deck.