Rakdos Joins Up + Starfield of Nyx + Mirrorhall Mimic // Ghastly Mimicry

Rakdos Joins Up

Starfield of Nyx

Mirrorhall Mimic // Ghastly Mimicry

How it works

1. Cast Mirrorhall Mimic by paying its mana cost. Choose to have it enter the battlefield as a copy of Rakdos Joins Up.
2. Put Mirrorhall Mimic into your graveyard due to the legend rule.
3. Mirrorhall Mimic's first ability and second ability trigger, along with Rakdos Joins Up's second ability.
4. Resolve Mirrorhall Mimic's second trigger and Rakdos Joins Up's trigger, dealing damage to target opponent.
5. Resolve Mirrorhall Mimic's first trigger, returning it from your graveyard to the battlefield with two +1/+1 counters on it as a copy of Rakdos Joins Up.
6. Repeat from step 2.

This loop relies on the legendary rule to turn Mirrorhall Mimic (cast and entering as a copy of Rakdos Joins Up) into a self-sustaining engine. Because you control two copies of Rakdos Joins Up, state-based actions force you to put one into the graveyard, which immediately triggers its own ability to return itself to the battlefield with two additional +1/+1 counters. Simultaneously, both permanents trigger their damage-dealing abilities whenever a legendary creature dies, allowing you to continually drain your opponent. While Starfield of Nyx isn't strictly necessary for the core loop, its presence highlights the enchantment synergy running through these legendary interactions, letting you recur your pieces if disrupted.