For Challenge # 043 but probably too wordy to fly. Still, fairly easy to combo into a complete lockdown.

That's a pretty good idea, it rewards working out exactly what might come up that's most problematic for you.

I'm not sure about cost -- even if you guess right most of the time, turn 7 is often a bit too late to help. But it can't be too cheap, as in a sanctioned tournament having everyone drag the game out while they try to guess and say what people are playing aloud is likely to be too disruptive.

Perhaps it should be moved to an ability on a cheap small-creature mythic, possibly as a repeatable ability like "T: Name a card. Target player reveals the next card he or she draws, and discards it if it's the named card." even though that's not right for this challenge.

I was thinking about the ability to break this with things to look at the opponents deck; and thus completely deny their draw. So it surely needs to be very pricey. Might be safer on a mythic creature body, I guess.

Let's try it on a body that size

Good point, if you can see their top card (which various cards do), it's an almost complete lock-out. And having a "good card that randomly wins if I have this other card as well" is pleasingly spikey. I don't know if that should be embraced or avoided.

Well, it was my intent, anyway. Whether it's a good intent or not, I have no idea. Looked at from that pov, putting it on a creature makes it a much less safe lock; which is probably reasonable.

That is a nicely Spike card.

As has been pointed out on other cards - probably doesn't help you quickly enough. Maybe I ought ot at least make it a hasty flier or something.