pokemon diamond and pearl great encounters booster box D&P Mysterious Treasures Pokémon Pack Great Encounters (TCG) - Bulbapedia,

Not much to cover with this promotion, only because its not as big nor popular as the McDonalds one but then again, that hasnt stopped people from doing crap like this: Can Poketubers stop doing TCG Breakthroughs, this is going way to far for a piece of cardboard

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Creature - Human Warlock Myojin of Grim Betrayal Myojin of Grim Betrayal enters with an indestructible counter on it if you cast it from your hand

Both of them do a good job of showing up the expansions new mechanics and key features, and after playing them I dont think a third one would have been necessary, especially because it would have just been another Ruby/Emerald like last time

The result is that if you can land both on the field you can fire the ballista ad nauseam, stacking counters on it and taking them off to inflict infinite damage and gain infinite life