pokemon cards boltund V (103/264) [Sword & Shield: Fusion Strike] – Plug Attack 2 Boltund 076/202 (Sealed) - Knock

That said, each of these cards is actually quite good with simple, powerful abilities that instantly get your deckbuilding brain going

combine it with a set of Squadron Hawks and it's effectively a Time Walk

While they won't outright stop a spell from being cast, it will slow it down by at least two turns, giving you some extra breathing space

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The trick is to use it as a political tool: If your opponent attacks you with The Void, they bounce off each other

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