Actually, under new targetting rules introduced since Splice was created, can't different instances of the word target on a spell refer to the same target, as long as the card doesn't specifically note that they must be different targets? Let me find the relevant rules passage...
Rule 409.1c; relevant passage highlighted
If the spell or ability requires any targets, the player first announces how many targets he or she will choose (if the spell or ability has a variable number of targets), then announces the targets themselves. A spell or ability can’t be played unless the required number of legal targets are chosen. The same target can’t be chosen multiple times for any one instance of the word “target� on the spell or ability. If the spell or ability uses the word “target� in multiple places, the same object or player can be chosen once for each instance of the word “target� (as long as it fits the targeting criteria).
Now, for this to be fair, I agree that the player from whom you're gaining creatures should always be the same player who is casting the spells. However, there is nothing theoretically wrong with Gerrymander's wording.
However, I can't say that I much like this card. It is, despite all of the careful concealment, a Time Walk variant. No matter what your opponent does, he or she loses a lot of tempo. Either he doesn't play any spells or he plays spells and loses permanents. In fact, I'd say there's few situations in which an opponent doesn't just want to pass their turn away. Now, on the other hand, this doesn't revoke your opponent's attack phase, which may be relevant. I suppose at that, it's worth a little bit less than Time Warp. I dislike Time Walk effects in general, but suppose this one is fair.
