While they dont always look the same and have slightly differing abilities, there are usually certain aspects you can expect from a merfolk card
The ability to shut down the primary calling card of the format (commanders) without any thought or strategizing (compared to something like Nevermore, which you get locked into) just makes it undesirable
I dont see any issues playing Stasis
For instance, Surgical Extraction is played in the maindeck of several Modern decks Mardu Deaths Shadow, Izzet Phoenix, and Azorius Control each run it but none of those decks will play more than two copies
You can't choose to pay any additional costs for the copy
Worldly Tutor comes in at $20, Entomb at $16, Mystical Tutor at $13, and Gamble at $11