ryuan
From Zero to Hero!
Sion would hypothetically trade those stones with a Zelretch alternate self from the point of this Z's view.How did Sion trade philosopher stones with an alternative self?
Edit: Why only 99%?
As for being 99%, you took the pieces that could be seen by common sight alone, but 'microscopic' traces of the infection remained. You used soul radiotherapy to kill the rest.