Dualcaster Mage + Thunderous Debut + Mortuary + Ashnod's Altar

Dualcaster Mage

Thunderous Debut

Mortuary

Ashnod's Altar

How it works

1. Cast Thunderous Debut by paying 6 and sacrificing an artifact, enchantment or token.
2. Holding priority, cast Dualcaster Mage by paying 1.
3. When Dualcaster Mage enters the battlefield, it triggers, copying Thunderous Debut.
4. Activate Ashnod's Altar by sacrificing Dualcaster Mage, adding CC.
5. When Dualcaster Mage dies, Mortuary triggers, putting Dualcaster Mage on top of your library from your graveyard.
6. Resolve the copy of Thunderous Debut, causing you to look at the top twenty cards of your library and put Dualcaster Mage and up to one other creature card onto the battlefield.
7. Repeat from step 3.

This ingenious loop centers around Thunderous Debut, which you cast and bargain to set up the engine, utilizing its powerful ability to dig twenty cards deep into your library. While that spell waits on the stack, you drop Dualcaster Mage with flash to copy it, immediately feeding the Mage to Ashnod's Altar for colorless mana while simultaneously triggering Mortuary to seamlessly place Dualcaster Mage right back on top of your library. When the copied Thunderous Debut resolves, it plucks the Mage—alongside any other creature you desire—straight back onto the battlefield, letting you repeat the entire sequence indefinitely for infinite mana and all your creatures on the battlefield.