[bbz]

hmm its not wrong the master is last to cast, but the slaves start casting personal luck/luck/body ethereal instead of soul slay, I think as its said they don't get the extra astral levels if they want to cast a spell, while if the caster casts a spell they get fatigue for that spell as if they were S3 casters(even though they don't cast the spell themselves).
though if you have the master casting power of the sheres, and light of the northern star then they get to S3 and can start casting.

To Deathjester : Did you by any chance try that communion without the communion master casting power of the spheres and light of the northern star?