I really like the Invocations for this set. A lot of the arts are fantastic, and I really enjoy the "theme" of destruction and power within the selected cards, particularly when it comes to something representing Bolas, like Omniscience and such. Almost all the cards seem really neat or powerful, even if they have costs and such to make them overall unusable.
I understand and agree that making Masterpieces for every set means they're likely to scrape the bottom of the barrel, not helped by them starting with LANDS, the single most important card type in the game. I appreciated the themes for later blocks, like Kaladesh block having artifacts and such, but it led even then to really...underwhelming cards. I pulled 2 Masterpieces. 1 in Kaladesh (Painter's Servant) and 1 in AER (Staff of Domination). Cool cards, but I was really upset with Staff because of how mediocre it is as a card. Servant at least had some weird niche role it could fulfill, but Staff's effects were costly and not very strong on their own.
These Invocations (and many of the Amonkhet ones), I would probably have been "happier" to pull, because those cards were more epic in a sense, and felt more playable to some extent. And these being so representative of the crazy shit hitting the fan in the story just makes me more excited to see the story develop and other cards being revealed.