See Challenge # 129.

I originally envisaged this making tezzeret and sarkhan vol tokens, but decided that maybe I should go hog wild and have a planeswalker that makes other planeswalkers in general. That's not quite what the challenge says, but hopefully it's close enough?

I'm not sure about the exact costs of the abilities, or the "gain control" ability. Or if the last ability should have a fixed cost instead of X.

I can't about costs, though the second and third ability feel like distinctly blue abilities. Maybe + ability is one too high for his starting loyalty, though I don't play any formats where any of the high-cost planeswalkers really drop to know if killing them with damage is something that actually happens to them.

I think that the -X could include opponents' libraries as well though. That might feel more Bolasy.

I agree the second ability is more blue in the colour pie, but the third doesn't have much precedent. It's like Diabolic Tutor inasmuch as it's like anything.

I designed this without the second ability and then looked around for something else that would fit, so this is more blue than I originally intended. I would quite like it if this was BBU or BUU, given Bolas' other planeswalker card. But BU seems appropriate, given that #1 is B, #2 mostly U, and third black but with a heavy blue influence.

Yes, search opponents' libraries. That won't usually make a large difference but is a lot lot more Bolas-y :)

It would be cute if the third ability allowed you to blow up opponents' planeswalkers with the legend rule, but it would be a lot of extra complication and mostly superfluous given the second ability.

I feel that the third ability should be "Search target player's library for a planeswalker card with CMC X or less and put it onto the battlefield." That would be more standard wording.
Otherwise, this is quite fun! I particularly like the first ability. It's a bit narrow in scope, though. I really don't think the middle ability needs to cost 4 loyalty.