Trench Behemoth + Fastbond + Crypt of the Eternals

Trench Behemoth

Fastbond

Crypt of the Eternals

How it works

1. Activate Trench Behemoth by returning Crypt of the Eternals from the battlefield to your hand, untapping it.
2. Play Crypt of the Eternals, triggering it and Fastbond.
3. Resolve the Crypt of the Eternals trigger, causing you to gain 1 life.
4. Resolve the Fastbond trigger, dealing 1 damage to you.
5. Activate Crypt of the Eternals' first ability by tapping it, adding C.
6. Repeat.

By leveraging Fastbond, you bypass the normal one-land-per-turn limit so you can replay Crypt of the Eternals as many times as you like, with the minor life loss easily offset by the land's own entry trigger. Each time you play Crypt of the Eternals, you tap it to add colorless mana before using Trench Behemoth's activated ability to bounce the land back to your hand and untap the Behemoth itself. This recursive loop generates infinite colorless mana, infinite landfall triggers, and infinite lifegain triggers in Vintage format.