Notes & Combos
The Big Picture
This is Cardian Burn, the gameplan is going first and inflicting damage via the spell Synch Realm. Cardian Lightshower (Synchro level 8) can also inflict damage in the opponent's Draw Phase. In either case, you hope to win before your opponent gets to play.
Through repeated use of your best draw power Willow (level 11) and Moonflower (Synchro level 6), you find the cards you need to keep comboing and to inflict damage to your opponent.
You can fill the extra deck more than this, I was on a budget.
Technical Notes
There's a lot to be said about Cardians, but 2 cards deserve special attention:
Super All In! has a lot going on, read it thoroughly. To activate it, you must have at least 4 monsters in your GY, and zones to summon them to. The risk of Super All In! can be avoided if Lightshower (Synchro level 8) is on feild at time of resolution, as this prevents your monsters from being destroyed.
De-Synchro has some rulings to keep in mind too. The exact materials used for the synchro summon are the ones which get summoned back, you must be able to summon all of them. This means you need enough zones to summon all the cards. And any cardian with a summoning conditon (those with 1000 atk or higher) must have been properly summmoned first.
Shuffle back your oldest cards first, so you don't accidentally get rid of something you needed for De-Synchro.