To reach the huge being you must travel deep below the most treacherous place. There is a little known isle called 4 square isle. You must find an opening and enter hole, let the water take you down a waterfall. You must battle Kelpies to the end of the road.

speak 'wistolia pearigal wermalin'
speak 'time'
speak 'not too gross'
speak 'rainbow'
command 'owrfdrg'
to leave this sacred place command 'mirror'
This will take you to the dark guardian above Ralyx.

Another Teacher is one found on Middle Continent. She is located near the lamia, on the platue. There is a path that leads down in the middle of the platue, where giant snow leopards dwell. Search the debris and unlock her secrets.