This spell was totally pissing me off today. Geno can testify, this one guy, Dildo Saggins I believe his name was, would spam this spell hardcore, reminded me of Meroibo with his PK spam. Geno said that the save for the spell is Fortitude, but my build had 21 fortitude, so the requirement to counter the spell must be uber. Basically what this guy would do is cast time stop to keep you from moving, then Bigby's to keep you in one place once time stop wore off, then he would cast missle storm. Not a bad strat, but I think the save should be lessened.
Also, someone reported some kind of bug dealing with timestop...not sure on all the details to this one though...