The main point of this deck is to control your opponent by linking of their important materials and popping their cards before they are able to capitalize on them. The deck takes practice and requires you learn the balance of popping your own cards versus popping your opponent's cards. There are a lot of times where you intentionally die by battle just to proc effects and extend plays. This deck also has a lot of battle phase shenanigans with Rakea, Abominable, and Escape of the Unchained.
A few explanations:
Interrupted Kaiju Slumber: Dark Hole that gives both players Kaijus. Notably this allows you to use Unchained Soul of Disaster to link with the Kaiju given to your opponent. 4 Kaijus is a good ratio I believe. You can certainly run more, but I don't think the field spell is a great inclusion because it isn't searchable and doesn't always give you the value you would like. Opening Kaiju Slumber, any twin, and the field spell however can end on Soul of Rage backed by multiple negates, so if you can find a consistent way to do so, run wild with it.
Dark Spirit of Banishment/Malice: Self-recurring handtraps that summon your level 8 unchaineds out of grave, with Banishment also redirecting an attack in the process. Note that they negate the effect of the summoned monster so you can't then use Abominable to pop or Disaster to link off opponent's monsters, but if Disaster is destroyed his grave effect will still fire.
Witch's strike: Popping backrow against Unchained is just a bad idea. I'm doing that myself half the time anyway. This is a very nice power trap that blows out the opponent. Helps a lot in the Guru matchup. This can be replaced with any 3 cards of your choice.
The extra deck: You pretty much just need the Unchained links, the other stuff is really just utility. Unicorn is nice because you can make it on the opponent's turn to get that additional shuffle. BLS link is pretty easy to make with a level 7 or higher. Dingirsu allows you to handle things you can't normally. Borrelsword exists for the sole purpose of outing Ultimate Falcon, you typically don't OTK or when you are in a position where you could you're probably locked into summoning Fiends. Masterking is really only made when you have a Dark Spirit summoned off of Tour Guide you need to put in grave. There is so much flex space in this extra deck. Everything in here has come up once or twice at least, but there's probably better situational links/rank 8s.