Silver comes with an Iblis Biter (From Sonic 2006, the first game he appeared in, appropriatly) however look at his box, they mis-spelled it as LBLIS instead of IBLIS which is fairly important.
Here is the Iblis Biter accessory that came with Silver. As you can see, it's not super like the game, because of the size (it was bigger in the game) and there's no "lava like" effect on the surface, it's simply red. This is likely to be the weakest-link accessory that any of the figures had packaged with them. It's still ok, but it's not as super as some of the other choices. Also, this is likely to be uncommon, as for some reason, not a lot of Silvers appeared during the run of the line, and he seems to have been released later than other figures too.
Photos by TheCPKStudios