Aveline de Grandpré

Because face-down creatures don’t have a name, they can’t have the same name as any other creature, even another face-down creature.

If a face-down spell leaves the stack and goes to any zone other than the battlefield (if it was countered, for example), you must reveal it. Similarly, if a face-down permanent leaves the battlefield, you must reveal it. You must also reveal all face-down spells and permanents you control if you leave the game or the game ends.

The face-down spell has no mana cost and a mana value of 0. When you cast a face-down spell, put it on the stack face down so no other player knows what it is, and pay 3 generic mana to cast it. This is an alternative cost.