It takes little time to realise this is not the case. One after the other, they lead people to the edge of the temple's influence. Not one can pass. 

This does not cause them much worry. They have no way of knowing whether it is only these villages who are still infected. Perhaps the nearness of the temple has left them with just enough mana to carry the plague? They have no way to tell. Without mana of their own they can hardly use the Bow, never mind telling how much mana anyone else might have. They widen their search, bringing people from farther away.

When all these are unable to pass as well, they pause. A few villages might have been a worthy sacrifice, for the return of magic. But this many? There is no cure for the mana plague. Any who cannot pass the temple wards will die once the seal is broken. And if two thousand years was not enough time to excise the plague from humanity... 

They try a few more times, luring a few curious or mercenary enough to respond to their stories or coin. Two from across the continent, and one from even farther - but none of them can pass. 

Despairing, they abandon their quest, secluding themself in the temple where at least they can remove their Null Amulet and feel their own mana. 

Unknown to them, however, their actions have left a legacy behind, and a tradition forms among the youth of the nearby villages. 

Ask any in the village of Hardhome and they will tell you that Thom Morton is not exactly the brightest boy around. Good-hearted, undoubtedly, his kindness is obvious in his everyday actions, from helping with errands in the village, to assisting the elderly Fen Derring with her garden, and even watching the local children while their parents go about their business. He's friendly with the other boys his age, if sometimes mocked for his difficulty picking up on subtleties and his sometimes nervous disposition. A good boy, but not a smart one, or one given to great acts of bravery.

So when the townsfolk hear of him going off into the woods outside town, the only worry they have is that he might give into his fear and get lost running away from the traditional test of courage. 

When he doesn't come back within the day they send out a small search party, expecting to find him fairly quickly. When the party comes back empty handed that night, his parents insist on sending runners to the nearby villages to look for him. 

However, before they can leave, the ground begins to shake. 

They're in the deepest parts of the temple, where they've set up their living quarters, when the shaking starts. Startled, they leap to their feet from the nest of cushions and blankets they were curled in, focused on a complicated bit of Life magic they've been working on for about a decade at this point. They run out into the corridor, up the three flights of stairs to the Seal room, pulling their Null Amulet on in preparation to head outside to see what's happening. However, they find the cause of the disturbance before they can.

Sprawled over the alter is a human boy, perhaps mid-adolescence. The Staff is gone from its place, fallen to the ground at the boy's side - he's pulled it out. 

The Seal is broken.