In addition, it instructs you to exile a card from the stack instead of sending it anywhere else
You can basically scry the top of your library equal to your basic land count, which can be a lot as your color count increases, and then in a Five Color format with at least 300 cards redundant ramp like this which can have added value is not nothing
Thassas Oracle doesnt even need to be in play when its trigger resolves in order for you to win, and should someone Stifle your first attempt, youre still in the game to try again
Two other artifacts, Chaos Wand and Bag of Devouring, send cards into exile, the Bag provides good protection mechanisms for creatures affected by spells or abilities
In the latter, it was used on paper printed version of digital-only Alchemy cards on MTG Arena
The creature featured in Subtlety is a great, albeit somewhat petrifying concept, and the imagery does well to bring it to life