Just dropping this here, I hardly use this deck anymore but I used to use of a LOT.
The main deck is basically built out of this:
Tefnuit engine:1x Wattaildragon
3x Hieratic Dragon of Tefnuit
1x Hieratic Seal of Convocation
This is the setup that allows me to spam rank 6 XYZ. Since I don't really run backrow, I will either have field advantage or disadvantage. If I'm at an advantage, I obviously don't need to do much other than use the field. If I'm at a disadvantage, Tefnuit can easily bring me back to having an advantage. Messier is my favourite rank 6 XYZ and the fact that you can bounce cards from your grave to your hand is ridiculous. I've done this a lot:
1. XYZ to Messier 7;
2. Bounce back REDMD from grave to hand;
3. XYZ to Gaia Dragon;
4. Use Gaia Dragon to summon REDMD;
5. Use it's effect to summon another dragon (like Lightpulsar or Prime Material).
Lightsworn Engine:2x Lyla, Lightsworn Sorceress
2x Ryko, Lightsworn Hunter
1x Charge of the Light Brigade
The main mill engine. This creates field advantage (Ryko flips and kills anything, Lyla kills s/t) and fills the grave at the same time.
Destiny Heroes engine:1x Elemental Hero Stratos
3x Destiny Hero Dasher
2x Destiny Hero Malicious
1x Destiny Hero Fear Monger
3x Destiny Draw
This supports the Tefnuit engine. All Destiny Heroes (except one) are level 6 and can be tribute summoned using Tefnuit, or have a great effect from the grave. It also gives me a lot of draw power so I can get my key cards fast.
Chaos Dragons:1x Red-Eyes Darkness Metal Dragon
3x Lightpulsar Dragon
2x Darkflare Dragon
The raw power next to the XYZ. It uses the attributes of the Destiny Heroes and Lightsworn to be summoned. They can also help Destiny Heroes go to the grave from the hand (especially aimed for Malicious).
Other support cards:1x Black Luster Soldier - Envoy of the Beginning
1x Chaos Sorcerer
The whole deck is filled with Dark and Light monsters, so these two are obvious. Not to mention that Chaos Sorcerer is a level 6 monster.
2x Tragoedia
1x Gorz, the Emissary of Darkness
Defense from hand, Tragoedia can also become level 6.
1x Prime Material Dragon
1x Caius the Shadow Monarch
Rank 6 monsters with good effects.
2x Effect Veiler
Stops pesky Rabbits and such.
1x Allure of Darkness
1x Heavy Storm
1x Dark Hole
1x Monster Reborn
1x Treacherous Trap Hole
All obvious choices.