Must Eat a shiny stone to enter.
You require approximately 45 Vampire tokens, These tokens drop from Vampire boss's located in the royal minion spawns on the east side underground. Once you get these tokens you go into Dark knight of vanda, Walk north west and talk to Culex. He will give you a bunch of missions Of which you hand him the tokens each time. You will then Require a Vamperic crest which is dropped from Vlad the boss that spawns in venore.
Once this is complete you are required to go into the portal to your north, and kill Culex. Now be warned Culex requires 3 players. 1 knight and preferably 1 Shooter and 1 SIO/Shooter.
Culex also drops your magic level to 0, So Knights, Bring pots!
From Here You get given a piece of string. You go into the yielothax spawn and loot the ring of ending. Now you put the ring on, and use the string on the ring (Ensure you are in the DP to do this)
You can now kill culex whenever you please and have the chance to loot rare items.