This is probably the most throw away entry I've ever done in the A to Z Challenge across all of my blogs, but I really couldn't think of anything else to use. This will, however, offer another short post, which I'd imagine most people will appreciate.
Yesterday I spoke about the X Casting Cost; how it was used and some of the rules bound to it.
Simply put, the "Y" symbol is just another "placeholder for a number that needs to be determined" and follows all the same rules as "X" where applicable (though, I don't think it's ever been used in a card's casting cost, it's mostly used in abilities).
Considering the use of "Y" is apparently obsolete, much of this is moot.
Have you ever played a card with a "Y" value? Do you know of any other cards that have a "Y" value? Can you think of any Magic: The Gathering product beginning with "Y"?