Shifting Blade, Prototype

When Shifting Blade, Prototype enters the battlefield, you may put a Shroud counter on it.
If you do, switch its power and toughness.
As long as Shifting Blade, Prototype has a
keyword counter, it can't be blocked.
(This includes any keyword other than Shroud.)
A mysterious Aniloid with an amnesiac
manufacturing process, and three DNA Souls...