Oko, the Ringleader + Vorinclex, Monstrous Raider + Spark Double

Oko, the Ringleader

Vorinclex, Monstrous Raider

Spark Double

How it works

1. Cast Oko by paying 2, causing it to enter the battlefield with six loyalty counters due to Vorinclex.
2. Cast Spark Double by paying 3, choosing to have it enter the battlefield as a nonlegendary copy of Oko, and to enter the battlefield with eight loyalty counters due to Vorinclex.
3. Activate an Oko's third loyalty ability by removing five loyalty counters from it, causing you to create two token copies of each other nonland permanent you control.
4. If you created any legenedary tokens this way, put all but one of them into your graveyard due to the legend rule.
5. Repeat from step 3 using a different Oko.
6. Once you have infinite Oko tokens, you may instead activate Oko's other abilities.

This loop kicks off by casting Oko, the Ringleader, whose entry—alongside every loyalty counter manipulated here—is doubled by Vorinclex, Monstrous Raider's replacement effect, ensuring Oko starts with a massive six loyalty. When you follow up with Spark Double, it enters as a nonlegendary copy of Oko boasting eight loyalty counters thanks to Vorinclex, letting the two planeswalkers coexist without violating the legend rule. From there, you can activate one Oko's −5 ability by removing five loyalty counters, copying every other nonland permanent you control—including the other nonlegendary Oko—to endlessly multiply your board state and generate infinite copies of your permanents.