Time Sieve + Myr Battlesphere + Planar Bridge + Soldevi Digger

Time Sieve

Myr Battlesphere

Planar Bridge

Soldevi Digger

How it works

1. Activate Planar Bridge by paying 8 and tapping it, causing you to search your library for Myr Battlesphere and put it onto the battlefield.
2. When Myr Battlesphere enters the battlefield, 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 Soldevi Digger by paying 2, putting Myr Battlesphere on the bottom of your library from your graveyard.
5. Repeat each turn.

This ingenious loop relies on Planar Bridge as your engine, demanding a hefty eight mana and a tap to pluck Myr Battlesphere straight from your library and onto the battlefield. The moment Myr Battlesphere arrives, it floods your board with four Myr artifact creature tokens, neatly providing the exact five artifacts needed to satisfy Time Sieve's sacrifice cost for an extra turn. Once Myr Battlesphere is safely in the graveyard, Soldevi Digger steps in for a modest two mana to tuck it back onto the bottom of your library, ensuring Planar Bridge can find it all over again next turn.