Anyway, in the final part of the solution where you said that I should enter the altar and with that killing myself and the druid it's not a good ending. I found a better ending which is using the Magic Cube on Lawson instead before entering altar on Druids' Chamber then you get a totally different ending. You will fly the rocketship with the three other druids and went home.
Acknowledgement
Annotated by alexvin for the RPG Gamers archive.