Too Spooky

Too Spooky's base power becomes equal to the creature with the highest power on the battlefield and it's base toughness becomes equal to the creature with the highest toughness on the battlefield whenever Too Spooky deals damage to a player and stays that way until the next time it attacks a player.
"Imagine if it found the true horror of a nuclear holocaust scenario. Now couple that with an entity that possesses shape-shifting abilities with no known limits, and you'll understand why it's classified as Keter."