Hmm. This looks way to expensive at first glance, until I realize that most non-conditional library topping in white already costs about 4. I have no idea what this should cost.

White gets better creature removal than Desert Twister that's for sure. This is clever; I like it. But I'd down cost it by at least two.

And yet Aethertow is 4. And it has the attacking restriction. (Admittedly it is hybrid and has conspire, which might drive the cost up a little.) There's also Griptide. This is a little more expensive but it has split second and the bury effect. On the third hand, Unexpectedly Absent will normally be cheaper than this... so maybe ?

If I removed "an opponent controls," this could be fairly useful on occasion to use on yourself. Perhaps a little too useful

Hmm. Set up your next several draws, at the cost of a creature, and 6 mana? Doesn't seem overpowered to me. Sometimes worth doing, but far from broken.