At the moment, this whole set idea is very much just an idea, and everything I put here is subject to change. Hydrate springs from the idea that, while there will be no blue cards, there will be a few cards that benefit from using blue mana, and perhaps some things with activated abilities requiring blue. Blue mana on this plane is incredibly scarce, but not nonexistent. There's just not enough to support blue creatures or inspire blue spells.

One of the problems with this is, of course, whether or not it's better than Mana Leak, which is already very powerful.

Well, I'd definitely play this without the blue. Current articles from LaPille seem to suggest that Mana Leak is too powerful for the core set as it stands right now. I wouldn't be surprised if they don't do:

­Lightning Bolt : Shock :: Mana Leak : [Worse than Mana Leak]

But they haven't, so that's not on the table. What I'm saying, though, is that "Counter target spell unless its controller pays " would probably be a fair spell for blue. It crazy good in white. Is that acceptable? I guess that depends on your definition of acceptable.

I viewed it as Mana Tithe+, which, of course, was in that-block-of-which-we-do-not-speak. I do wish this could stay at 2 CMC, but I think I'll do it at 3 for now.