Thanks a bunch. There's a lot of great feedback here! I'll try and convince my friend to get a Mox Sapphire, but I'm not sure if he's got enough for an Ancestral Recall as well.

About the Timetwister, I agree with you guys when you say that it won't really win games on its own, but I think my friend's rationale behind his wanting a Timetwister is the fact that he's trying to construct an aggro U/W control deck that will likely have a stasis lock in place by the second or third turn, with traditional serras for damage. He wanted a Timetwister to help replenish his hand in the late game, when the lock is firmly in place and his opponent will have limited means to retaliate or make use of the fresh cards.

However, I do agree that Mox Sapphire would most likely be the best pick, as it would accelerate his early game and will most likely be useful in other decks he might want to play.

I've been playing Magic for a long while now, but I stopped for a few years and I recently picked it up again, so a lot of my old skills are rusty. I was helping a friend (a new player) to construct a U/W control deck with white weenies, Serras, counterspells, and Stases. It's not really very common for new players to start off with older formats, but I guess he listened to me talk about which kind of Magic I preferred and got sucked in. Then my friend found out about the Power 9 and he really liked those cards, so he set aside some money to buy one of them. After some thought, he narrowed it down to  either Mox Pearl/Sapphire or Timetwister. He likes the moxes (he'll only get one or the other, but that's a different story) for the early mana acceleration and speed advantage (think second turn Serra), but he also likes the Timetwister because it's a way to draw cards in the late game when he's low on cards in hand and he'll be able to get back spells that were worth casting the first time around. He asked me which he should pick and I really can't decide.

My question is, which do you think would be better in a U/W control deck if you could have only one of them?

Thanks.