Time Sieve + Biotransference + Helm of the Host + Master of Waves

Time Sieve

Biotransference

Helm of the Host

Master of Waves

How it works

1. At the beginning of your combat phase, Helm of the Host triggers, creating a token copy of Master of Waves with haste.
2. The Master of Waves token triggers, creating a number of 1/0 Elemental creature tokens equal to your devotion to blue.
3. Activate Time Sieve by tapping it and sacrificing five creature tokens, causing you to take an extra turn after this one.
4. Repeat each turn.