I reviewed Raiken, and in case you don't find what I wrote on Raiken's thread, I'm reposting what I wrote here. Also I do not have a champion I want you to review yet, so let's just say you owe me one for now, okay?
Your character is very interesting, but a few suggestions seem necessary,
1) Without knowing Raiken's stats, his abilities will be harder to balance, so please keep that in mind.
2) The passive is perfect, and very unique, please don't change it, ever.
3) "Lightning Dash" has a very small range, 250, is barely enough to chase, or really hit any enemy, considering that Raiken is a melee champion. You're only real hope is if you have your sword sheathed, at the time.
4) "Move as Shadow" doesn't really make sense to me. Since he tumbles towards your cursor, you can't target an enemy, making his damage, and knock-up useless.
5) I really liked "Strike from Void", as it would help kill off those amazingly annoying tanks, so no changes there.
6) Major questions about "One Strike, Two Cuts" are, how much is it's base mana cost? Is there any cooldown?
7) When will you be posting up the lore, and the actual stats?
All in all this was very interesting to read, and I will be looking at this kind of frequently. Good Luck with future endeavors!