Oh, that's very nice. I would have thought 4/2 for 4 mana was too good (it's certainly an excellent flier in limit if it's common), but I hadn't thought of putting that drawback on a mid-size creature, it actually looks fairly balanced.

It's a pretty minor drawback on a creature more suited to attacking anyway - but then, is only very slightly undercosted in my opinion for a creature without the drawback.

Saying that - this may be more in relation to what I think costs ought to be - Phantom Monster - than what they actually are.

That was my thinking. 3U 3/2 seems to be standard for common now (and blue doesn't always get one of those), but 3/3 wouldn't be unreasonable if the set is strong on creatures or flying, and 4/2 is normally a bit better than 3/3, depending on situation, but not unreasonably so.

I think I have about the same "what costs ought to be" as you. And I think they are usually about right in that most fliers costing 4 will be <=3/3, only a small proportion will be 4/4 with a giant upside, and those will be rare -- it's just that standard constructed decks will always play that one ridiculously powerful card. (See also, mythic rares :))

So, is this balanced? Or should I drop it to a 3/2?

This is high-enough in power level that I think it'd normally be uncommon, or 4/1 at common. But the idea seems okay. 3/2 would be silly when there's Snapping Drake getting reprinted all the time.

Pretttty sure this exact card already exists. Because you inspired me to turn my (functional, horribly annoying) blue control deck into a (probably rubbish) lots of flyers deck. :)

Nope. The closest is Phantasmal Forces.

Ah, I was thinking of Cloud Spirit and Rishadan Airship, both being cheaper and 1 smaller.

I was looking at Skywinder Drake, the most recent iteration, as I was making this. I wanted something a bit bigger.