Alright, Grunny been meaning to ask. What this 'attunement' thing about?
Grunny doubts it about running all over zOMG to attune to purple crystals, so inferring from mention of 'cl.11+' that it something to do with DMS.
It's being able to use the 'bat door' in DMS, that will warp you straight into the green maze (second stage of caves). To do this, you need to go through the yellow and green mazes and also 100% room and see Kamila, and then complete a follow-up quest to kill 100 minions. It can be a very time-consuming process to do all of this, especially if the crew doesn't have much green maze experience.