One "ping" from Oliva can reduce any Eternal Witness or Snapcaster Mage to a memory, rather than a card
If left unanswered, Vren will take over the game in a turn cycle or two, guaranteed
Under the proposed solution we came to, we'd instead keep track of one quantity for all the printings of a title a player had collected, unlocking the use of distinct printings when the player collected a single copy
Even outside of this protection from everything silliness, if you've ever played a game with Tidal BarracudaTidal Barracuda in play, you're well aware of just how much it takes over your average game
Kellan, the Kid Free stuff Kellan, the Kid is a three-mana green, white and blue 3/3 with Flying and Lifelink