In the past, there was one way I believe kept Smokey from escaping the island . . . it was the Numbers which contained the EM forces (so Smokey could not attain full power). The Numbers were the magic spell combination lock to keep Smokey in place. Now, I can see the possibility of Smokey getting all the Candidates (which represent The Numbers) to Hydra expecting that his invisible chain to the island be broken, but in a twist of fate, the Numbers activate and "seal" Smokey away forever.