Look for these signs that a card is promotional
As with most things in Magic, however, I encourage you to do your own research on Gatherer or Scryfall as well there are a lot of blue mass removal spells beyond those in this post, and while they will generally be the best options for many blue Commander decks, some metagames and strategies can allow you to benefit a lot from a niche effect or specialized variation
As I explained in a previous column, for a while I was responsible for the vast majority of alternative win card in the game (we finally hired some other designers who also thought alternative wins were cool)
It's a really fun card that can do really hilarious and powerful things, but it also costs four mana and doesn't do anything right away, which makes it a tough sell in competitive decks
The two most valuable cards from the set are blue instant Intuition, a surefire way to search your deck for a specific card, assuming you have multiples, and Earthcraft, a built-in combo maker with any number of other spells