Great for a third flash
For a third animation, it's very impressive.
Work on improving your proportions. I wasn't impressed with your first ninja. It seemed as though you tried to make him muscular, but the attempt didn't quite work out. He seemed thin. The Grey Ninja looked far more impressive, though. Good work with him.
Your blood also needs a little work. It looks more like red explosions. Also, when the Blue Ninja is on the ground, the blood didn't seem fluid.
The storyline is easy to pick up, and you do an excellent job of telling it. Your use of anime techniques is very effective, and doesn't seem overused.
You also chose a good song for the scene. It establishes the tension and does a great job of pushing the movie along.
There's potential here, SamurEYE. Keep it up!