Creature - Wizard Skeleton Frost Titan Whenever this creature becomes the target of a spell or ability an opponent controls, counter that spell or ability unless its controller pays
It is a big price to pay to give up on Lurrus of the Dream-Den, which is arguably the best card in Modern, yet this big flyer justifies that price all on its own
In the right deck, it's extremely easy to trigger and a surprisingly effective way of winning the game
Clement, the Worrywort Clement has a reputation to uphold as the safest adventurer in Valley
Because it's not enough to just win your next Commander battle, you have to win the right way
Obvious contenders are Snapcaster Mage and the like - creatures that accrue their value when entering the battlefield or in response to an opponent's attempt at a maneuver, and can then be used to counter a new threat later