Intimidation Tactics Adding cycling to a discard effect is very cool, and improves the card when you draw it and your opponent doesnt have cards in hand
Part of what keeps its cost down is the vast number of reprints of the proper card, but also alternates like the spellshaper, Silverglade Pathfinder, or the lesson Shared Roots
Voltron decks often acquire these components by using either Auras or Equipment
You choose two of your creatures, they get much more powerful, and only they can attack in an additional combat phase
Liliana planeswalkers cover a range of abilities, but they often care about making players discard or sacrifice cards, which aligns with blacks general themes, and zombies, which relates specifically to Lilianas prowess as a necromancer