[Edi]

There is no such thing as immortality for sale in Dom3. There is the Elixir of Life which will resurrect a commander killed in battle (during battle, so he could be killed again) and the other methods mentioned. That's it.

The only way to get immortality would be to morph the caster to an immortal form, but that shapechanging spell is random and only a handful of the ~1800 creatures in the game have immortality to begin with...

Edi