Its not a permanent counter effect, so your opponent can replay the target on the next turn, but late in the game, you can play this as a 3/3 flash creature that sets them back a turn while you add to the board
Mill (Average, Synergistic) Several card games have the rule that if your deck runs out of cards, you lose the game
Avatar: The Last Airbender Rare Lands The rare lands from Avatar: The Last Airbender are nearly worth spells on their own and have almost no drawback as mono-color lands
But Im certain theres a deck that could be made in Legacy that can leverage this card Im looking at you , Urza
So, even though it's not destroying anything, you can actually prevent not only the Ba Sing Se that is already on the battlefield from making any relentless 2/2 attackers, but all future copies of Ba Sing Se