Yikes! This is so much better than Bone to Ash, Cancel, Dream Fracture, and Scatter Arc.
...Wait. Colorless mana? Oh. Maybe it's not as good as I thought.

It's kind of as a basic cost (where is the symbol for "colorless only"), which sounds somewhat fair to me given that will get you Cryptic Command, and then it gets significantly harder (at least in a format without Sol Ring...). I considered , but I thought that was just a bit too much.

Hmm. But this card also reads ": Counter target spell. Draw four cards. You may only use half of the non-basic land and/or artifact mana ever printed to cast this spell."

That's pretty damn good for an instant. Even if this didn't counter a spell, I'd probably pack this card in my deck over Opportunity (which might not even be correctly costed nowadays... we haven't seen anything as... focused... as opportunity since 7th edition).

Also, if my opponent showed me Imprecate mana, I wouldn't even bother casting spells anymore. It wouldn't be worth giving him 4 cards. So even if the card is fair, it could devolve the game into an unfun board state...

Possibly this might be better at ?

(Not sure if jmg is saying Opportunity is over- or under-costed; Tidings was printed more recently and has the standard -for-degrade-to-sorcery-speed discount.)

Also, this is one of those amusing cards like Etched Oracle that make you want something like Sphere of Resistance to increase the cost of your own spells.

Bah, you're right. Tidings is better. I was indicating that Opportunity might be too good by today's standards. I'm not sure... but it's probably fine. They've really been monkeying with that Tiding cost and space lately, though. I'm waiting for them to reprint Library of Lat-Nam and make the depowering of blue draw-sorceries official. ;)