1. At the -20L I had 6 soul gems after killing the boss, and bought antimagic ring for it. 1 soul remained.
2. I found second anti-magic ring in the dungeon. No effect, as expected.
3. I lost to the Illusionist, and started from the start of the 20-10 zone.

But... I haven't antimagic ring anymore, and haven't any souls too! :(