Myr Propagator + Umbral Mantle + Ashnod's Altar + Training Grounds

Myr Propagator

Umbral Mantle

Ashnod's Altar

Training Grounds

How it works

1. Activate Myr Propagator by paying 1 and tapping it, creating a token copy of itself.
2. Activate Ashnod's Altar by sacrificing the Myr Propagator token, adding CC.
3. Activate Myr Propagator by paying 1 and untapping it, giving itself +2/+2 until end of turn.
4. Repeat.

This clever engine uses Training Grounds to slash the activation costs of our mechanical army, making Umbral Mantle and Myr Propagator incredibly efficient to cycle. By equipping Umbral Mantle for free, our original Myr Propagator can use its discounted untap ability to power the loop while Ashnod's Altar converts our spare tokens into the mana needed to keep producing more copies. As you sacrifice each token to Ashnod's Altar, you generate a surplus of mana that fuels the entire process, resulting in an endless cascade of creature creation and sacrifice.