Mirrorpool + Splendid Reclamation + Tiller Engine + Coastal Hornclaw

Mirrorpool

Splendid Reclamation

Tiller Engine

Coastal Hornclaw

How it works

1. Cast Splendid Reclamation by paying 3.
2. Holding priority, activate any number of lands you control except Mirrorpool by tapping them, adding at least 2C.
3. Activate Coastal Hornclaw by sacrificing a land other than Mirrorpool.
4. Repeat step 3 until Mirrorpool is the only land you control.
5. Activate Mirrorpool's second ability by paying 2C, tapping and sacrificing it, copying Splendid Reclamation.
6. Resolve the Splendid Reclamation copy, returning all land cards from your graveyard to the battlefield tapped.
7. When the lands enter, Tiller Engine triggers that many times, untapping the lands.
8. Repeat from step 2.

This ingenious loop uses Coastal Hornclaw to whittle your battlefield down until Mirrorpool is your sole remaining land, allowing you to safely sacrifice it to copy the very spell powering the engine. When you cast Splendid Reclamation, it floods your graveyard's lands back onto the battlefield tapped, which immediately rouses Tiller Engine's triggers to forcefully untap them all. Because Tiller Engine untaps those lands instead of letting them enter locked down, your newly replenished mana base can instantly feed the next iteration—letting you repeat the entire process to generate infinite mana, landfall triggers, and magecraft triggers.