This clever setup creates an endless loop of counter manipulation and token generation by turning two creatures into a self-sustaining engine. Grim Poppet starts the cycle by stripping its own -1/-1 counters to place them elsewhere, which conveniently fuels Flourishing Defenses to flood the board with Elf Warrior tokens every single time a counter moves. Meanwhile, Spark Double joins the fray as a non-legendary copy of Grim Poppet—thanks to its copying effect—allowing it to pass -1/-1 counters right back to the original Grim Poppet and trigger Flourishing Defenses all over again. By bouncing the counters back and forth between the two matching threats, you generate an unbounded army of creature tokens and endless enter-the-battlefield triggers.