I'd assume the reason Deon didn't know who the survivor was would be because he thought he _had_ killed them all.
which brings up the possibility that Zastra is another surviving god, possibly from the Order side of things.
She could be setting up Deon to fight Raksis (removing the last Chaos God) in hopes that he'll be weakened enough that she can take him by surprise and kill Deon (and then become the world's sole deity).
___________________________
"I've always wanted to be somebody, but I should have been more specific." - George Carlin
which brings up the possibility that Zastra is another surviving god, possibly from the Order side of things.
She could be setting up Deon to fight Raksis (removing the last Chaos God) in hopes that he'll be weakened enough that she can take him by surprise and kill Deon (and then become the world's sole deity).
___________________________
"I've always wanted to be somebody, but I should have been more specific." - George Carlin