At present we are unable to do anything in the twilight forest as the bosses cant be attempted until the previous boss is defeated. How ever in order to unlock the achievement line for the twilight forest you must get the first achievement which is create a portal to the twilight forest. However, every time that I try to create a portal to the twilight forest it fails and I am told to use the nether portal version. Is there a way to either create the portal to start the achievement line or another way to gain the achievement? any help would be greatly appreciated.