In Japan, the set introduced the core mix of Pokemon, Trainer cards, and Energy, which is the basic structure the game still uses
Whether to include one card over the other comes down to specific environments, and larger Cubes could certainly facilitate both, but the point is that Callidus Assassin is a very real card for control decks that would like to spend their turns leaving up mana for counterspells and removal
Which is not exactly hard to see why
Well, things have changed a lot over the years, and while traditional fantasy settings remain at the center of the franchise, its canon Multiverse opened up almost endless possibilities, including themed crossovers with properties like The Lord of the Rings, Final Fantasy, and even Marvel
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