Nim Deathmantle + Krark-Clan Ironworks + Iron League Steed

Nim Deathmantle

Krark-Clan Ironworks

Iron League Steed

How it works

1. Activate Krark-Clan Ironworks by sacrificing Iron League Steed, adding CC.
2. When Iron League Steed dies, Nim Deathmantle triggers, causing you to pay 4 to return Iron League Steed from your graveyard to the battlefield, and attach Nim Deathmantle to it.
3. When Iron League Steed enters the battlefield, its fabricate ability triggers, creating a 1/1 Servo artifact creature token.
4. Activate Krark-Clan Ironworks by sacrificing the Servo, adding CC.
5. Repeat.

This elegant loop turns a modest construct into an engine for infinite mana and sacrificial yields by tightly closing a loop between the graveyard and the battlefield. When you feed Iron League Steed to Krark-Clan Ironworks, its death triggers Nim Deathmantle, which kindly offers to fish the Steed right back out of the graveyard for four mana while reattaching itself. Because Krark-Clan Ironworks's mana ability yields two colorless energy and the Steed's fabricate ability generously drops a 1/1 Servo artifact creature token upon its return, you can sacrifice that very Servo to the Ironworks to generate the remaining two mana needed to pay the Deathmantle's resurrection tax.