I don't think you can get another crystal. The crystal puzzle kind of blindsides you but it's no biggie.
As for the swamp monster, I assume you're a Warrior? You can't walk across the bottomless swamp, but perhaps there's a way to bridge it?
Hint:
Click here to view the secret text
×Try chopping down the big tree?
Hopefully that's a start. You might not be able to with the gear you have, once you know about that bit it's pretty logical from there on.
If you're non-warrior, AFAIK you can't cross the swamp and never have to.
[Last edited by Spiffo at 02-04-2014 08:40 PM]