Black doesn't have the ability or the capacity outside of cards like Vedalken Orrery to compete with what Blue decks normally do
Cards like Unruly Catapult, Galvanic Juggernaut, Traxos, Scourge of Kroog, Staff of Compleation, Bender's Waterskin, and the game changer, Mana Vault all have ways to untap themselves
Sythiss passive ability to gain life and draw cards for each enchantment you cast in addition to its low casting cost make it an effective way to start building up a fort and passively generate advantage while you do it
Players opening The Aftermath Boosters quickly found that they were accumulating duplicates of uncommon cards after just a few packs
Some of them have to stay in the settlements and raise pigs for the warrior orcs to eat when they get home
Hard to replace exactly, but if you're really looking for a way to draw extra cards when your opponents do look no further than