It allows you to look at and play the top card of your library at any time, and you pay life rather than pay the mana for spells you cast this way
Either way, its my go-to color pair, and let me tell you: theres never been a better time to play it
Black does have the monopoly on recursive one drop dorks and that lets it be more aggressive and abuse the non-token triggers better than other colours
Consider the difference between Etali, Primal Storm and Etali, Primal Conqueror, two creatures with very similar abilities, except Primal Storm triggers on attack rather than ETB
A good rule of thumb is this: during buyout season, try to be a net seller
Just be ready to pull out a calculator: even Magic Hall of Famer Paulo Vitor Damo de Rosa had trouble deciphering how the spell worked initially, and thats without cost reduction in the mix