Its a big difference between EU (Endless Universe) and AEU (Advanced Endless Universe).
Endless universe:
- You need Toxin to enter.
- To get Toxin you have to finish that quest like which GGB mentioned in his guide (
http://epicpw.com/guides/endless-universe-(eu)-guide)
- Entrance is at bottom of "pyramid" and you get in by talking to a NPC after you get toxin.
- There is only 1 possible version of this instance.
Advanced endless universe:
- You enter by walking into portal on top of the "pyramid"
- You need Jade Dragon Order to do this instance
- There are 3 possible versions and you need all 3 for titles.
Hope its a bit more clear now