Phyrexian mana uses no slash on this site.

Yes, and I posted a bug report (128175) about it. (The rules specify the format with the slash; see rule 107.4f.)

That does make sense, considering it's a "hybrid" mana cost. It doesn't change how to get the current system to display what you want, though.

I agree that it makes sense for that reason; not only that, but that is what the rules of Magic: the Gathering says to use, too.

I can't argue that it's in the rules, but I think official text representations of mana symbols are currently about as important to the rules as 100.6b — it has zero impact on gameplay. It also has zero impact on custom card creation, because it doesn't matter whether it's correct or not.

I'm not saying Alex shouldn't add {p/W} as an alternative way to produce . It's probably a good idea, if that's the way the custom card community commonly communicates that symbol. I'm just pointing out that the way you're trying to apply the rules is a bit silly. They don't govern card creation in that way.

The name is... ugh.

So I assume this is an effect you want each deck regardless of color to have access to, no? Since that's what the design does. The card is already heavy sideboard material which even further pushes it into being ubiquitous.

Not all names here need to be perfect or even good. Sometimes it's just about coming up with a filler name to get your idea across.

See: Most cards I make.

If something's a filler/code name then I often use quotation marks around it to denote that... though supposing if most were, then eh yeah.

I dunno, a 'nixian nix is quite a pleasing punny name.

It sort of feels od for everyone to be able to freely-counter; but then, they can only counter things anyone can do. And, I guess, some unusual forms of copying. So maybe it's ok.