Since the 7.21d change to Dream Coil, it now gets dispelled by:

1. Manta Style
2. Mirror Image
3. Phantasm
4. Omnislash
5. Infest
6. Assimilate
7. Supernova

It should work like Invoker's Deafening Blast, which is dispellable by only the following sources of spell immunity:

1. Black King Bar
2. Blade Fury
3. Rage
4. Life Break
5. Duel (with aghs)
6. Rolling Thunder
7. Battle Cry (with talent)