Ooh, I like that idea. It'd be a bit tricky to pull off, but it'd give some more feedback both to Blocking at a good time and to landing (or taking) a big hit with Thunder.
Maybe I'll have Electromagnet Shuriken ignore Block or Defense. As it is, it's a bit hard to justify putting it in a Trinket slot. EDIT: Also, I'm taking off the Variance on it. I must have Copied/Pasted player counterattacks.