This deck is for casual play (Do not try it in tournament, please)
The goal of the deck is to destroy board with gandora cross and after that summon levianeer, DAD and all friends dragons.
We can tutor Gandora X or Levianeer with Witch of the Black Forest who can be special summon with "magician girl" monsters in the battle phase. Omni Dragon Brotaur can tutor all dark dragon monster of the deck to prepare the late game board.
We can normal summon Gandora X with token of Fires of Doomsday or samsara dragon or special summon it with Red eyes Darkness metal dragon or Apprentice Piper.
Ghost ogre and snow rabbit is here to destroy annoying monster or spell/trap cards.
And for finish with the monsters, Marshmallon are just here for say "Yes it's a yugi muto deck, YES".
These spell/trap cards are non essentials, there can be replace by what you want, except Magical Contract Door (for fun and be accurate with the movie).
And extra deck is just a bunch of cards there can be useful but also good for Eater of Millions
Have fun :D