His ability to play a 6-cost Song for free makes him a must-inclusion in most lists, setting up a powerful turn 4 play
There arent any schemes that particularly synergize with the manifest theme, and the landfall schemes, like This World Belongs to Me and Your Fate Is Thrice Sealed, aside from sounding like Coheed & Cambria tracks, would be fine additions to most scheme decks, but especially to this one
Would you ever play this on the first turn
its treated as a special action. Special actions are things you can do that dont use the stack
It can protect your team from Night of Souls Betrayal effects, so maybe its worth having just one
If you have other cards that you're more likely to cast on your second turn other than Luminary, then you should treat it as a four-mana spell, as that is when you are likely to cast it