C854 (Grey Door)
[High] == Open on certain criteria being met.*
     00 = Main boss for the area is dead.
     04 = Mini boss for the area is dead.
     08 = Torizo for the area is dead.
     0C = Enemies Dead matches Enemies Needed.
     10 = Always closed.
     14 = Delay in Tourian Gate room.
     18 = Eticoons/Dachora saved?
[Low] = Index of the door.

*Set high bit (ie- add $80) to make this door re-appear every time you enter the room.
