Number 39: Utopia is a very protective Rank 4 XYZ monster. Its best use it to protect another weak, yet important monster, something you want to keep alive until at least your next turn. It can also stop your opponent from crashing recruiters like Pyramid Turtle and or Mermail Abysslinde into your ATK position monsters.
Utopia can certainly backfire, however. He can only negate two attacks. After that, he leaves you extremely vulnerable, and your opponent can attack it with literally any monster to destroy it.
Utopia is a risky monster to make, but making him at the right time can be incredibly powerful.
Evigishki Merrowgeist is a very proactive Rank 4 XYZ monsters, and one of my personal favorites in the format. Ideally, you want to make him to attack and negate the effects of one of your opponent's monsters in battle.
Evigishki Merrowgeist truly shines because it negates some of the most important monsters in all of Nova Format, including: Baobaboon, Blackwing - Pinaki the Waxing Moon, Dandylion, Elemental HERO - Shadow Mist, Giant Rex, Harpie Harpist, Mermail Abysslinde, Mystic Tomato, Nefarious Archfiend Eater of Nefariousness, Pyramid Turtle, Sangan, Sinister Serpent, T.G. Warwolf, World Carrotweight Champion, and more.
That being said, Evigishki Merrowgeist is not exactly easy to use. In particular, it can backfire if you use it to attack a facedown flip effect monster, which it will not negate. In many cases, Merrowgeist will require you to make correct reads on both monsters and backrow.
Diamond Dire Wolf is a highly versatile Rank 4 XYZ monster. In most decks, it works like an Exiled Force that can target any card on the field. However, in decks that run a higher percentage of Beasts, Beast-Warriors, Winged Beasts, as well as our old friend, Scapegoat, Diamond Dire Wolf will often have the opportunity to sacrifice another floater and then head into battle.
Generally speaking, when you make Diamond Dire Wolf, you will be sacrificing board presence in order to out a particular card on the field. This decision sounds a lot easier than it is in practice, especially when you consider the fact that choosing not to make another XYZ monster is also an opportunity cost.
Another factor that keeps Diamond Dire Wolf in check are the lack of good targets being left on the board. Many monsters in this format are either floaters, replaceable, or indestructible, and whenever you target a set S/T on your turn you run the risk of hitting something chain-able.
Overall, Diamond Dire Wolf is a core component in the toolbox that makes duels more dynamic. Cards on the board are by no means safe with Diamond Dire Wolf lurking in the Extra Deck.