Limited Wish and lowering opponent's saves

[Coldheart]

Going through the description of the Limited Wish spell, I came to the point where it says:

Quote:

Produce any other effect whose power level is in line with the above effects, such as a single creature automatically hitting on its next attack or taking a –7 penalty on its next saving throw.

I could not find an answer on the messageboards and in the FAQ, so the question is: How does it really work? Limited Wish says there is no saving throw to its effects, so can a wizard automatically impose a penalty to the creature he/she casts this spell on? It seems a bit overpowered.

[Isil-zha]

It is a seventh level spell. If you compare that particular result to bestow curse for example it does not seem to be overpowered.