Sapphire provides card draw, items, and ink resource management abilities
You can enhance them further with Panharmonicon, Strionic Resonator, and Brago, King Eternal
Because it counts the death of any creature, you will find that this gains that counter a decent chunk of the time
You don't want to play a deck focused on attacking with creatures You want a deck fully committed to Go Tall or Go Wide strategies (this deck is somewhere in between) You want a deck concept that you can fully upgrade/optimize without spending tons of cash (5C Dragon upgrades can get expensive!) Blood Moon is a thing in your playgroup If you like where this deck is going, then great
In Pioneer, meanwhile, there's a Mono-Black Discard deck that seems ready made for Hostile Investigator
If you do, return this card from your graveyard to the battlefield tapped and attacking