Ninja Assassin Dude

Reveal Ninja Assassin Dude when you draft it, and choose a number.
This spell costs {x} less to cast, where {x} is the number you chose.
{1}{u/b}: Return target creature you control to its owner's hand. Activate this ability only during your turn. This ability costs an additional {x} to activate, where {x} is the number you chose.