Shadow of Mortality gives this core a second threat to fill that role making Street Wraith and Dismember more appealing options
For a truly high-value item, the ultimate security is getting it authenticated by a third-party grader like Beckett
They are also much more convenient to lay as a land drop later in the game than shock lands
And this doesn't have the modern templating of "return target creature an opponent controls" as you can bounce your own thing
Legendary Creatures/Planeswalkers Matter Dominaria may support artifacts and sagas, but legendary creatures and planeswalkers are definitely the main focus of the set: not only do we have legendary creature support (Arvad the Cursed) and planeswalker support (Oath of Teferi) but we even got a brand new type of sorcery, the legendary sorcery (Primevals' Glorious Rebirth), which require you to have either legendary creatures or planeswalkers
I will admit it's a fairly derpy card in some ways, but the ability to steal the highest life total, or give the Archenemy the lowest life total is very strong in practice, and it can create really big swings for something like Exquisite Blood or Vito, Thorn of the Dusk Rose to generate even more value from