Myr Turbine + Time Sieve + Myr Battlesphere + Barkform Harvester

Myr Turbine

Time Sieve

Myr Battlesphere

Barkform Harvester

How it works

1. Activate Myr Turbine by tapping it and five Myr, searching your library for Myr Battlesphere and putting it onto the battlefield.
2. When Myr Battlesphere enters, it triggers, creating four 1/1 Myr artifact creature tokens.
3. Activate Time Sieve by tapping it, sacrificing Myr Battlesphere and the four Myr tokens, causing you to take an extra turn after this one.
4. Activate Barkform Harvester by paying 2, putting Myr Battlesphere from your graveyard onto the bottom of your library.
5. Repeat each turn.