Musket was cheap so I spent some time with it and thought I'd share.

If Fuwa'd/Maxx C'd you CAN droll yourself. You won't be able to add Mutiny or S/T off Caspar which means you lose the Musket piece and have to choose between Caesar or Desirae(ie basically standard TwinSmith board).

With just Ki-sikil and no "extender" in hand(1cc) you lose out on 1 end board piece between Caspar, Ceaser or Desirae, your preference.

Near the end when you bring back Sunny with A Bao it needs to be able to point to an open space after making Caesar in order to make Agnumday since Caesar will be placed in EMZ.

You want 2 open spaces in the main monster zone at the end. 1 for A Bao to return to and then the other free space for the twins. Mutiny in the Sky's gy effect can clear an extra fiend off the board otherwise on your following turn the twins can be used for "free" to return it your hand.

Opening Buio or Mutiny means you can skip Aerial Eater which also saves you needing to make an extra body(make FS lacrima -> Summon LF, LF+Requiem=Necroquip, FS Lacrima + Necroquip = Ceaser, or just summon engraver and skip necroquip)

Nibiru: Depends on when dropped. Being Fiendsmith it can still make a board via engraver.

Droll: Combo has 2 draws and 2 adds. The 2 draws are optional. If you skip them the order of the adds are Mutiny -> Musket S/T so you would potentially lose 2 disrupts unless you have another S/T to trigger Caspar on opp turn. If you open mutiny then this can play around droll