Myr Propagator + Umbral Mantle + Ashnod's Altar + Biomancer's Familiar

Myr Propagator

Umbral Mantle

Ashnod's Altar

Biomancer's Familiar

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 loop relies on transforming Myr Propagator's cloning ability into an engine of exponential growth. Biomancer's Familiar acts as the crucial cost-reducer, dropping the activation costs for both the copy ability and Umbral Mantle's untap effect down to just one generic mana each. By using Ashnod's Altar to sacrifice the token copies you generate, you continuously cash in for the exact mana needed to fuel Umbral Mantle's untap, leaving your original Myr Propagator ready to flood the board with an infinite army.