Anyway, exactly what do these 'boxes of Orden' do?
You have two good options for learning about that:
Option one: Read the Sword of Truth series.
Option two: Read the rant about the Boxes of Orden I'm about to write.
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(I don't know how it is in this game, but I can tell you how it was in the books...)
There are 3 boxes of Orden, no more, no less. Each one comes with a "cover". A box with a "cover" on it cannot be opened. The "covers" can be removed using magic, revealing a box of pure black.
In order to open a box: you must have at least one of them, then you can "put it into play". This gives you significant magical protection(for instance protection from the Sword of Truth)(I assume this is why TDS is unkillable), enables you to open a box, once you have all 3, but will kill you if you have not done so by the first day of winter. You do not need all 3 Boxes of Orden to put one into play. Once somebody has all 3 boxes of Orden, whoever has all 3 may open one of them at any time. One box grants whoever opens it godlike power. One of the two wrong boxes... kills the opener, and tears a hole in reality(let's hope that doesn't happen) that opens into the underworld. The other wrong box... kills everything. In order to determine which box is the correct one to open, one must preform complicated magical rituals and have access to a specially made sanctuary built to allow said rituals to be possible.
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In short... I wouldn't be too surprised if TDS was lying about some of the aspects of his role. I learned that his statement "I have a role that stops everyone from winning" was true, but if that meant that his role could
possibly stop everyone from winning(everybody dies box)... hm.