Do you have to 'free' Rezo to get to New Khodar?

[Rincon]

I'm stuck in Greenwort/Messelandar (sp?)/Freedom Islands unable to get access to New Khodar/Riftland.

I've seen from other threads that you reach these places through the cave on Griffin Island but that cave isn't activated for me.

I am level 37 and have defeated Guildor once. The only other main quests that are open is gaining Audience with the Elf King and talking to Rezo.

Unfortunately, I can't find a 3rd elventir and am unable to defeat the undead army "guarding" Rezo.

Is it possible to open up the new worlds without accomplishing the above?