The release of Valkyrie's Rage box has strengthened some monster types that needed support because they were rarely seen in play. Increasing the chances and consistency of decks based only on Fairy and Dark type for example, with cards like Sky Scourge Enrise, Dunames Dark Witch, Escape from the Dark Dimension and the addition of Spirit monsters with its support cards. It has many versatile cards which can fit in different deck ideas.
Soul Exchange makes tribute monsters more viable and might make some changes in the meta game. Running multiple copies of this card in a deck with high level monsters might turn a duel around, since not only can you summon a big monster for a cheaper price, but you also destroy an opponent monster, regardless of level, type/attribute, or stats. You won't be able to attack the turn you use it, but this weakens their defense while strengthening your attack.
Negating some card effects:
With cards like Angel O7 and Divine Wrath, you can effectively negate or prevent enemy monster's effects, while Xing Zhen Hu is used to lock down 2 cards that your opponent set, preventing them from being used.
This new pack introduces a new monster type with its own unique style. Spirit monsters are monsters that always return the turn they are summoned, but this pack also includes their support cards, cards like Mirror of Yata and Shinobird Power Spot will empower them and also covers their weaknesses.