Bouncing a bit 'cause I had weird ideas about the show while in the shower

As awesome the lineup is, there's still the issue of the god-like status that Kiske will have, coronating more than 20 years of dreams by both those those who have seen him back in the day, and those who didn't. He's by far and away the biggest attraction of the tour, if Kai Hansen skips because he needs to bring the metal to Mars or something, people would still go to see Kiske.
So this puts Deris in a bit of disadvantage, he's still the house keeper and "master of ceremonies" so to speak, but for once he will not be the main attraction with the spotlight on him.
If they split the sets, letting Kiske sing his songs and then Deris sing his own... case one, Kiske starts and then people will be bored through the Deris songs. Deris starts, people will anticipate Kiske all the time.
The best solution is to approach it the Avantasia way, with singers coming and going, and they should alternate between 2-3 songs each.
Still, who goes first? Kiske opens with the first song, and everyone forget that Deris will be there as well. Deris opens up, and still people will want Kiske to show up asap. So the best solution is a duet.
On which song? they should go for HALLOWEEN.
First of all, it's a kickass and bold opener. You come to the show to see the enlarged line-up, Walls of Jericho inevitable intro and them BAM..... 13 minutes of german power metal straight in your face!!! It was insanely awesome when they did it in 2007, and to see Kiske and Deris coming out together would make the HD awesomeness of 2007 a 4K awesomeness ten years later.
I can also picture half the song duties in my head: Deris would just shout at the beginning "Masquerade, masquerade!" with Kiske having the first verse, he can have the second. Deris also is more suited for the more sinister parts of the song, like the "I am the one, doom's in my hands" section... and what comes after, "I'll show you passion and glory - he is the snake" begs for a duet.
Then after Halloween they can alternate two-three songs each, Deris for me is still the house singer so he should be the one, after this imaginary duet, to say "Ladies and gentlemen please welcome back Michael Kiske". It feels weird to think the other way around, Kiske introducing Deris as first dialogue with the audience. And then they can swap songs back and forth - Keeper of the Seven Keys would work well as a set closer - and I guess the very last song will be another duet with I Want Out, with Kiske holding out the looooooooooong note at the last chorus while Deris sings it.
...am I daydreaming too much?
