Notes & Combos
The only important extra deck cards are Verte + DPE, Anima (gets a bit more utility from fiendess), and Underworld Goddess as a Crooked Cook out.
Prosperity > Extravagance because you need field spell or fusion destiny to play.
1 Final Battle because of space. Its not a bad draw but you'd rather have something that stops board building/backrow removal. It is your wincon against Eldlich. Don't forget 4th mode stops called by on Fiendess.
No Umastryx becuase it takes too long to set up, is terrible in your opening hand, and it's utility is not important in the meta.
2 Flex Slots = 2 IDP because its a good answer to eldlich, weird stuff like megaclops, and 2-for-1's GY decks.