Three black mana and half your life will net you a 4 card draw
I just think the card is well executed it being an artifact plays well with Urzas Saga, Improvise and Springleaf Drum, and unlike Thalia, Guardian of Thraben where youre locked out by the tax, you have the choice with Esper Sentinel which presents interesting in-game decisions as you have to balance the tax on the mana versus providing your opponent with card advantage a similar decision to that of being on the play or on the draw
Wizards of the Coast has steadily increased the power level of these decks over the past few years, meaning modern precons can hold their own at a casual table right out of the box
Sure, those elements are staggered out over multiple turns, but its still a ton of value for your opponent to compete with
In particular, it is revealed that the identity of Oh In-sun's original character, a low-class monster, is related to this side