So I'm fighting Miraak at the Apocrypha Summit and I'm at the part where he absorbs his third dragon soul. How do I get him to stop being ethereal? I gave up last night because I couldn't figure it out. Reloaded my save from before I entered Apocrypha this morning and tried again and I still can't figure out how to get him to come out of his Ethereal Spirit shout.

I know I must seem pretty stupid to have not figured this out yet, but I tried every shout at my disposal. It's probably something really simple I'm overlooking.

Weapon that does damage + lots o' health pots.

But seriously, it's bugged. If you do too much damage in one hit he will become stuck in the etheral state.
You have to slowly chip away is health to avoid it.

Well, now I feel dumb. I thought I had to yank him out of his Shout somehow. Thanks Ledgend.