Ashaya, Soul of the Wild + Blossoming Tortoise + Spawning Pit + Tezzeret, Betrayer of Flesh + Winding Constrictor

Ashaya, Soul of the Wild

Blossoming Tortoise

Spawning Pit

Tezzeret, Betrayer of Flesh

Winding Constrictor

How it works

1. Animate Spawning Pit using Tezzeret, Betrayer of Flesh
2. Activate Spawning Pit's second ability by removing two charge counters from it due to Blossoming Tortoise, creating a 2/2 Spawn artifact creature token.
3. Activate Spawning Pit's first ability by sacrificing the Spawn, putting two charge counters on it.
4. Repeat from step 2.