Grim Poppet + Flourishing Defenses + Mercurial Pretender

Grim Poppet

Flourishing Defenses

Mercurial Pretender

How it works

1. Activate Grim Poppet by removing a -1/-1 counter from it, putting a -1/-1 counter on Mercurial Pretender.
2. Flourishing Defenses triggers, creating a creature token.
3. Activate Mercurial Pretender by removing a -1/-1 counter from it, putting a -1/-1 counter on Grim Poppet.
4. Flourishing Defenses triggers, creating a creature token.
5. Repeat.