Felidar Guardian + Reveillark + Phyrexian Altar

Felidar Guardian

Reveillark

Phyrexian Altar

How it works

1. Cast Felidar Guardian by paying 3.
2. When Felidar Guardian enters the battlefield, it triggers, targeting Reveillark.
3. Holding priority, activate Phyrexian Altar by sacrificing Felidar Guardian.
4. Resolve the Felidar Guardian trigger, blinking Reveillark.
5. When Reveillark leaves the battlefield, it triggers, returning Felidar Guardian and up to one other creature with power 2 or less from your graveyard to the battlefield.
6. Repeat from step 2.

This elegant loop starts by casting Felidar Guardian, whose entry trigger targets Reveillark; by sacrificing Felidar Guardian to Phyrexian Altar in response, you bank a mana and send the cat to the graveyard. Blinking Reveillark forces it to leave the battlefield, triggering its ability to pull Felidar Guardian right back out along with another small creature. As Felidar Guardian re-enters to restart the cycle, Phyrexian Altar quietly converts every iteration into a limitless supply of colored mana, sacrifice triggers, and entering-the-battlefield effects.