Doubling Season, Tetravus, and Time Sieve

Prerequisites

• Doubling Season on the battlefield
• Tetravus on the battlefield
• Time Sieve on the battlefield
• Tetravus has at least one +1/+1 counter on it

Steps

1. At the beginning of your upkeep, Tetravus triggers twice
2. If Tetravus has fewer than four +1/+1 counters on it, follow these steps; otherwise, skip to step 7
3. Resolve the token making ability, removing all +1/+1 counters from Tetravus and creating twice that many Tetravite tokens
4. Resolve the token exiling ability, exiling those tokens and putting twice that many +1/+1 counters on Tetravus
5. Move to your next turn
6. At the beginning of your upkeep, Tetravus triggers twice
7. Resolve the token making ability, removing at least four +1/+1 counters and creating at least eight Tetravite tokens
8. Activate Time Sieve by sacrificing five Tetravite tokens, granting you an extra turn after this one
9. Resolve the token exiling ability, exiling at least three Tetravite tokens
10. Repeat from step 5

Results

• Infinite turns