Grim Poppet + Nest of Scarabs + Clever Impersonator

Grim Poppet

Nest of Scarabs

Clever Impersonator

How it works

1. Activate Grim Poppet by removing a -1/-1 counter from it, putting a -1/-1 counter on Clever Impersonator.
2. Nest of Scarabs triggers, creating a creature token.
3. Activate Clever Impersonator 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 clever loop relies on trading -1/-1 counters back and forth between Grim Poppet and a clone of it made by Clever Impersonator, letting you strip and replace the counters indefinitely. Every time a counter is placed on either creature, Nest of Scarabs triggers to flood the board with 1/1 black Insect creature tokens. Because the counters just bounce back and forth between the two creatures without running out, you generate an infinite stream of creature tokens and entering-the-battlefield triggers.