Some decks cant actively deal with the floodgates when they are faced-up and being used, making it an easy win
Creatures with undying, like Hound of Griselbrand, or creatures with persist, like Puppeteer Clique, make good bodies to sacrifice to casualty too
Historic Horizons utilizes its digital-only nature beyond these three recurring mechanics as well, with WotC saying it makes it possible to print cards with rules that wouldnt fit in a paper frame
Is the list too strong, or too weak in your opinion
The card was errata'd in 2017 (a massive 15 years after the card was first printed) with the introduction of Link Monsters to the game, but prior to then, the effect of Darkness Approaches was to flip a monster face-down without changing its battle position
Every trading card format needs specific storage options to maintain condition and accessibility