Prototype Portal + Gonti's Aether Heart + Thopter Assembly + Ashnod's Altar

Prototype Portal

Gonti's Aether Heart

Thopter Assembly

Ashnod's Altar

How it works

1. At the beginning of your upkeep, Thopter Assembly triggers.
2. Holding priority, activate Prototype Portal by paying 6 and tapping it, creating a token copy of Gonti's Aether Heart.
3. Gonti's Aether Heart enters the battlefield, causing you to get EE.
4. Resolve the Thopter Assembly trigger, returning it from the battlefield to your hand and creating five 1/1 Thopter artifact creature tokens.
5. The Thopters enter the battlefield, triggering Gonti's Aether Heart five times, causing you to get ten E.
6. Activate Ashnod's Altar five times by sacrificing the five Thopters, adding ten C.
7. Cast Thopter Assembly by paying 6.
8. Thopter Assembly enter the battlefield, triggering Gonti's Aether Heart, causing you to get EE.
9. Activate Gonti's Aether Heart by paying eight E and exiling it, causing you to take an extra turn after this one.
10. Repeat each turn.