Time Sieve + Mycosynth Lattice + Helm of the Host + Phylath, World Sculptor

Time Sieve

Mycosynth Lattice

Helm of the Host

Phylath, World Sculptor

How it works

1. At the beginning of your combat phase, Helm of the Host triggers, creating a nonlegendary token copy of Phylath with haste.
2. When the Phylath token enters the battlefield, its first ability triggers, creating at least four 0/1 Plant creature tokens.
3. Activate Time Sieve by tapping it, sacrificing the Phylath token and the Plant tokens, causing you to take an extra turn after this one.
4. Repeat each turn.