pic related
> I can't really see a mechanical or thematic advantage, so I stand to be enlightened.
It matches the rest of the set, both mechanically and flavor-wise. The set's lore is that it takes place mostly divided by two religions, one white-oriented and one black-oriented. Because of this, I want the set to feel like its unbalanced in favor of white and black, because its a plane where things are either one side or another. So I'm hoping with a bunch of cards like this on other colors (other than black and white), the set will carry on this feel.
Mechanically-wise, the set has many cards that are related with a permanent being either black or white, since its a war between both colors. This goes from simple "protection from black" to "T: destroy target white permanent". Basically, if there's a color in a text box, its either black or white.
Now, design-wise, I just think it looks cool, and its something that has never been done before in Magic, but I think could be done (by could be done I mean that its possible, not that wotc would do it). Its somehow related a bit with Chaos Planar's shifted cards, exploring the in-between of two colors.
> Celestial Order
"Dishonor" means turning it into a 1/1 morph? Do you use morph on your set?
> Protective Bushi
Underpowered, could be common.
> Serpentblood Hitokiri
At first I thought it was too strong, but then I saw Ambush Viper and realized its just an upgraded version. Also, boobies :D
Very cool!, but I'm not sure about the wording. Also, you should check whether it would return itself to your hand or not. If it wouldn't, you don't need the exile bit :)
I agree with . Very cool, but I would go for 6/6.
First of all, seems OP as fuck. Second, I believe that most graveyard-effects like this at least check whether you are really from that color (so that you don't break the colorpie). Check out the card "Anger".