The Eminence ability alone is enough to justify building around it
Protection and Consistency One of the last things you want to make sure that your deck consistently has is protection for any wincons that you choose to take on, and this can come in the form of counterspells like Dream Fracture as well as high-value recursion such as Seasons Past
The card was legal as a four-of all the way up to April of 1995, when Standard was first invented
If you gain an amount of life "for each" of something or "equal to the number" of something, that life is gained as one event and Leyline of Hope's second ability applies only once
[[Faith of the Devoted]] costs 1 each time you want to use it, but it is an enchantment, so it is harder to remove
But most of all, it's a lot of fun to watch your opponent's face fall as you play the spell they were hoping to draw