Normally Magic: the Gathering cards get banned because they are too powerful, but this isn't always the case
Metal Tail: 40 Before doing damage, you may flip a coin
Nether Void itself is a extremely powerful enchantment from Legends that makes everyone pay an extra three generic mana for all of his or her spells
Once per turn, when you take battle damage from an opponent's attacking monster: You can activate 1 of these effects
Liberator, Urzas Battlethopter Switching teams in the Brothers War, we have Liberator, Urzas Battlethopter, one of the most powerful living weapons in Urzas arsenal
Stardust Dragon (Original Art) Controversial opinion here, but this is the only main character card I actually love the artwork for