Rex, Cyber-Hound + Trench Behemoth + Skyshroud Ranger

Rex, Cyber-Hound

Trench Behemoth

Skyshroud Ranger

How it works

1. Activate Rex using Skyshroud Ranger'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 clever setup relies on Rex, Cyber-Hound absorbing the activated abilities of creatures in exile, transforming the hound into a one-dog engine. By using Rex to copy Skyshroud Ranger's ability, you can continuously drop lands from your hand straight onto the battlefield to trigger your mana sources. Then, Trench Behemoth's ability lets you bounce those very same lands right back to your hand while conveniently untapping Rex in the process. This creates a tight, self-sustaining loop that generates infinite landfall triggers and endless mana from any lands that enter untapped.