Magneto's is the ultimate herald-level multi-tasker. Holding off Thor via shields while he rips Vision into dust should be par for the course, and Namor can engage Thor long enough to make it a quick two-on-one match.
Im going with Magneto and Namor here. Magneto can either destroy or control Vision easily enough, and Namor is capable of fighting Hercules and Hulk, so Thor wont be that much of a stretch. Of course Namor cant beat Thor (as he cant beat Herc or Hulk), but him with Magneto and possible even Vision together, I do believe can beat Thor.
Right, but Magneto is the master of magnetism, etc, etc. Thor may be able to produce/effect magnetism with his hammer, but he obviously doesn't have near the feats that Magneto does. If Thor were to attempt a magnetism vs magnetism match, he'd lose.
Which isn't to say that Erik could effect the hammer, for all I know Thor could simply absorb the attempt.
He'd still more often than not lose a match against Mags and Namor though.
Thor wins even if Magento turns Vision against him as well.
The only person here who will give Thor any kind of trouble will be Magento, everyone else get's 1/2/possibly 3 shotted depending on how easy Thor is taking it.