Finishing Ancient Land of Ys

[helix@attila.apana.org.au (Alex Lee)]

OK, playing Ancient Land of Ys again, Inow stuck.  Near the end of the
game, in the tower, I've just killed a floating two headed boss.  The
passage out leads to a door which is protected by magic, and I just CANNOT
open it!  I've tried using the evil ring and necklace, tried only holding
silver objects, etc, etc.  What am I missing here!?  And where do I get
it!?  I have the Rod, BTW, which is supposed to grant me access to
SOMETHING...

I did finish the game 8 years ago, but I cannot remember how to do this
bit!  Could this possibly be a dud copy?  I'm playing the game using
Bernie ][ the Rescue, with a cracked copy.  Could the cracked copy have
stuffed up the game?  Although the disk's integrity is OK...

Any and all help appreciated!

LaTeR!