Rakdos Joins Up + Opalescence + Phyrexian Metamorph

Rakdos Joins Up

Opalescence

Phyrexian Metamorph

How it works

1. Cast Phyrexian Metamorph by paying its mana cost. Choose to have it enter the battlefield as a copy of Rakdos Joins Up.
2. Put Phyrexian Metamorph into your graveyard due to the legend rule.
3. Phyrexian Metamorph's first ability and second ability trigger, along with Rakdos Joins Up's second ability.
4. Resolve Phyrexian Metamorph's second trigger and Rakdos Joins Up's trigger, dealing damage to target opponent.
5. Resolve Phyrexian Metamorph'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 clever loop relies on Opalescence to turn our enchantments into creatures, setting up a state where Phyrexian Metamorph can enter the battlefield as a copy of Rakdos Joins Up. Because you now control two legendary enchantments with the same name, the legend rule instantly sends your Metamorph copy to the graveyard, triggering both its own abilities and the original Rakdos Joins Up's death trigger to deal damage. When that same Metamorph's enters-the-battlefield trigger resolves, it plucks itself right back out of the graveyard with extra +1/+1 counters to restart the cycle, letting you repeat this loop as many times as you need to melt an opponent's life total.