Now this card is obviously one of the most defining cards this game has seen in a couple of years. That being said, it is without a doubt needed to compete in today’s meta-game. TGU is a ran at three, and the main XYZ engine that this deck plays.Maxx “C”:
The way this card can gain you advantage in cards, or by literally stopping your opponent in their tracks is too good. Another thing I would like to say about this card, is that it does not harm this deck as much as it does Plants, Dino Rabbit, and Agents, which, in my opinion, is really useful.
Thunder King Rai-Oh:
Another strong turn 1 opener versus virtually the whole format. Stopping T.G. searches, as well as Sangan searches is great. Forcing your opponent to play around the ability it has to negate an inherent special summon is something to take into account as well, since we have cards such as Black Luster Soldier - Envoy of the Beginning, XYZs, and Synchros running around.
Black Luster Soldier - Envoy of the Beginning:
One of the main heavy hitters of the current format. The card is amazing. It can literally end the game in a heartbeat. And Chaos decks can summon the card with ease. If your deck can summon it in a consistent manner, then you have no reason not to run it.
This card is my absolute favorite card of the format. Stopping Dino Rabbit in their tracks is good. The ability to rip a card from your opponent’s hand via a direct attack is good as well. And the fact that it is a level three that will end up sitting there, unless your opponent wastes resources to get rid of it, then it will most likely be there for an easy Rank Three XYZ summon.
Now, the above cards are some of the most obvious choices for a chaos deck. I will go further into the discussion now with a few cards I find necessary, and help the deck in overall consistency.
This is one of the chaos monsters that has been around for the longest time. It’s an easy inherent special summon, with a pseudo Black Luster Soldier - Envoy of the Beginning type effect. It can banish a face-up monster on the field, dealing with annoying cards such as Gachi-Gachi Gantetsu, Stardust Dragon, Wind-Up Zenmaines, and even an opposing Black Luster Soldier - Envoy of the Beginning.
This card is a nice tech for Chaos decks, I think. It’s ablility to go into Chimeratech Fortress Dragon is really good, especially with the rise in popularity that Karakuri seem to be getting, and due to the fact that Wind-Up Zenmaines is also a machine. I like the card a lot in Chaos for the aforementioned reasons, as well as the fact that it is a light for BLS, and Chaos Sorcerer.
Another light target for BLS, and Chaos Sorcerer. This card has seen a decline in play due to the fact that Maxx “C” is ten times better, and the lack luster affect it has on Plants, and Dino Rabbit. I think this card might start seeing more play with the release of ORCS, though, since it hurts Ninjas, Inzecktorz, and Wind-Ups quite a bit.
Breaker the Magical Warriror:
I like this card as a 1-of, and it works really well. Being able to pop those Solemn Warnings/Dimensional Prison/Mystical Space Typhoon is pretty good, as well as honestly forcing the activation of the former two. Costing your opponent in lifepoints, or just a defense card they would need to stop a later push.
And last but not least I’m going to go over a few of the cards in the extra deck I find important, and then I will give you my decklist.
Number 20: Giga-Brilliant
I find this card extremely important. The minor attack boost is the least important part about the card, though it isn’t completely useless. It’s a Rank Three XYZ that is an instant BLS, or Chaos Sorcerer when brought out with TGU, due to it’s light attribute.
In my opinion the best Rank Three XYZ in the game right now. Another reason why Tour Guide From the Underworld is such a good card. A huge annoyance for your opponent. Definitely a great card to keep your opponent at bay while you build up your resources.
Leviair the Sea Dragon:
Another good Rank Three XYZ that you have easy access to. It’s a great follow-up play to a BLS, or Chaos Sorcerer drop. Allowing yourself to special summon the Thunder King Rai-Oh you just banished to special summon the earlier mentioned cards seems good.
I hope you all enjoyed this article, because I know I enjoyed writing. I feel things are a bit rocky, since this is my first one, but if I continue to do these, I know I will improve. Let me know what you all think! And now, I leave you with my Chaos decklist:
3 - Tour Guide From the Underworld
3 - Maxx “C”
3 - Thunder King Rai-Oh
2 - Spirit Reaper
2 - Chaos Sorcerer
2 - Effect Veiler
1 - Black Luster Soldier - Envoy of the Beginning
1 - Sangan
1 - Gorz the Emissary of Darkness
1 - Breaker the Magical Warrior
1 - Cyber Dragon
Extra Deck: 
2 - Wind-Up Zenmaines
1 - Leviair the Sea Dragon
1 - Number 20: Giga-Brilliant
1 - Number 17: Leviathan Dragon
1 - Number 34: Utopia
1 - Chimeratech Fortress Dragon
1 - Trishula, Dragon of the Ice Barrier
1 - Brionac, Dragon of the Ice Barrier
1 - T.G Hyper Librarian
1 - Stardust Dragon
1 - Scrap Dragon
1 - Ally of Justice Catastor
1 - Black Rose Dragon
1 - Orient Dragon
Side Deck: 
2 - Cyber Dragon
1 - Doomcaliber Knight
1 - Spirit Reaper
1 - Legendary Jujitsu Master
2 - Leeching the Light
1 - Mystical Space Typhoon
2 - Fiendish Chain
2 - Black Horn of Heaven
1 - Mirror Force
1 - Dust Tornado
1 - Compulsory Evacuation Device