https://metalitalia.com/articolo/avantasia-lo-studio-report-di-ghostlights/Lenghty italian studio report plus there's an interview with Sasha Paeth.
If you want have some fun with Google translator, here are the essentials:
Mystery..... well we all have heard it.
Let The Storm Descend Upon You is a complicated track, it looks like it may be about to end twice or thrice and then restarts again, heavy mid-tempo, it speeds up afterwards. Lot of details and vocal duels.
The Haunting has Dee Snider, but it's more in style with dark Alice Cooper, not Twisted Sister. Tobi wanted someone scary but not too much, a sinister approach that was not overly dangerous. Bluesy guitars.
Seduction Of Decay started as a tribute to Zeppelin's Black Dog, it evolved into something heavier and more sinister, Tate sings low and those tones suits him well. There are orchestrations with violins, there's somehow of a reminder of Suite Sister Mary.
Ghostlights is Kiske's song 'cause "no one else can sing high like him", classic power metal anthem.
Draconian Love is somehow gothic, mixes goth rock, soft Moonspell and power metal. Very low vocals by Herbie Langhans 'cause Tobi couldn't go that low.
Master Of The Pendulum is heavy and hard, both Tobi and Marco Hietala play evil characters. Riff is heavy as Edguy's Mysteria.
Isle Of Evermore is a new-age-ish ballad with Sharon. Described as a "bitter ballad".
Babylon Vampyres is a heavy song that showcases the guitar players, there are three solos, one is right at the beginning. It's all about the guitar work here it seems.
Lucifer is a ballad written for Jorn's voice, it's a piano piece. It ends when it seemed it could start into something heavier.
Unchain The Light is another power metallish song, the other one more in style with old Avantasia and Edguy, Kiske is in here as well.
A Restless Heart And Obsidian Skies is the classic Catley song, Tobi's part in it makes it heavier. Worthy closer.