Time Sieve + Myr Battlesphere + Harnessed Snubhorn

Time Sieve

Myr Battlesphere

Harnessed Snubhorn

How it works

1. Deal combat damage with Harnessed Snubhorn.
2. Harnessed Snubhorn triggers, returning Myr Battlesphere from your graveyard to the battlefield.
3. Myr Battlesphere enters the battlefield, creating four 1/1 Myr creature tokens.
4. Activate Time Sieve by tapping it, sacrificing Myr Battlesphere and sacrificing the four Myr tokens, causing you to take an extra turn after this one.
5. Repeat each turn.