Scarecrone + Su-Chi Cave Guard + Mirrorworks + Krark-Clan Ironworks + Tannuk, Steadfast Second

Scarecrone

Su-Chi Cave Guard

Mirrorworks

Krark-Clan Ironworks

Tannuk, Steadfast Second

How it works

1. Activate Krark-Clan Ironworks by sacrificing Su-Chi Cave Guard, adding CC.
2. When Su-Chi Cave Guard dies, it triggers, adding eight C.
3. Cast Scarecrone by paying 3.
4. When Scarecrone enters the battlefield, Mirrorworks triggers, causing you to pay 2 to create a token copy of Scarecrone.
5. Activate the nontoken Scarecrone's second ability by paying 4 and tapping it, returning Su-Chi Cave Guard from your graveyard to the battlefield.
6. When Su-Chi Cave Guard enters the battlefield, Mirrorworks triggers.
7. Holding priority, activate Krark-Clan Ironworks by sacrificing the nontoken Scarecrone, adding CC.
8. Resolve the Mirrorworks trigger, causing you to pay 2 to create a token copy of Su-Chi Cave Guard.
9. Activate Krark-Clan Ironworks twice by sacrificing both Su-Chi Cave Guards, adding CCCC.
10. When the Su-Chi Cave Guards die, they trigger, adding 16 C.
11. Activate the token Scarecrone's second ability by paying 4 and tapping it, returning Scarecrone from your graveyard to the battlefield.
12. Repeat from step 4.

This intricate loop turns the massive mana injection of Su-Chi Cave Guard into an unstoppable engine, fueled by the artifact-sacrificing prowess of Krark-Clan Ironworks. As you sacrifice and recycle your pieces, Mirrorworks steps in to duplicate both your threats and your utility engines, ensuring you always have a Scarecrone ready to pull the Cave Guard straight back from the graveyard. While Tannuk, Steadfast Second gives your evolving army haste and warp flexibility, it is the constant cycling between battlefield and graveyard that ultimately generates an infinite supply of colorless mana, tokens, and death triggers.