Grim Poppet + Nest of Scarabs + Flesh Duplicate

Grim Poppet

Nest of Scarabs

Flesh Duplicate

How it works

1. Activate Grim Poppet by removing a -1/-1 counter from it, putting a -1/-1 counter on Flesh Duplicate.
2. Nest of Scarabs triggers, creating a creature token.
3. Activate Flesh Duplicate by removing a -1/-1 counter from it, putting a -1/-1 counter on Grim Poppet.
4. Nest of Scarabs triggers, creating a creature token.
5. Repeat.

This loop relies on a clever shell game of shifting counters back and forth between Grim Poppet and Flesh Duplicate, using the static presence of Nest of Scarabs to extract a swarm of value from every single transfer. Whenever Grim Poppet strips a counter from its clone, Nest of Scarabs triggers to birth an Insect token, and turning right back around to fire a counter from Flesh Duplicate to Grim Poppet repeats the process. Because both creatures can act as both the source and target for these counter shifts, you can bounce the -1/-1 counters between them indefinitely to flood the board with endless tokens.