Rex, Cyber-Hound + Trench Behemoth + Scaled Herbalist

Rex, Cyber-Hound

Trench Behemoth

Scaled Herbalist

How it works

1. Activate Rex using Scaled Herbalist's ability by tapping it, putting a land from your hand onto the battlefield.
2. If the land is mana-producing and enters the battlefield untapped, you may activate it by tapping it, adding at least 1.
3. Activate Rex using Trench Behemoth's ability by returning the land from the battlefield to your hand, untapping Rex.
4. Repeat.

This loop transforms Rex, Cyber-Hound into a one-hound engine by feeding him the activated abilities of Scaled Herbalist and Trench Behemoth from exile. Scaled Herbalist allows you to drop a land back onto the battlefield, while Trench Behemoth lets you return that very same land to your hand to untap Rex, resetting the process. If your lands enter untapped and produce mana, this continuous cycle generates infinite mana alongside an endless stream of landfall triggers.