There should be a badge/award for being able to defeat a boss without being able to move, because it is surprisingly more easier to stay completely frozen and kill a beast than it looks
The "Screamer" attack has actually pretty loud noise effect, so if you have any heart problem or are extremelly sensitive please turn down your volume before using it!
I think the Achievements page should have a counter for the achs like "X slayed X enemies" or "You purchased X runes", so it could be easy to keep a track of things like that.
Sometimes the little guy wouldn't thrust, but that's because it would be extremely overpowered, imagine it, flashing across the dojo without getting killed.
If you keep an eye on your ninja, you can see how it does a simple melee attack where he's standing.
Or at least that's my theory.