Dusk Legion Zealot

Black's oldest bargain, pay life and draw a card, arrives here as a single cast with a body attached. Where Phyrexian Arena and Underworld Connections meter that exchange across turns, this front-loads the whole transaction: the life payment is fixed at one, and the card lands as soon as the enters trigger resolves. That structure is what makes the 1/1 nearly free in any deck that wants to keep its hand full while still putting bodies on the board. A sacrifice deck gets fodder that replaces itself; an aristocrats shell gets a death and an enters trigger in the same package; a token or reanimation strategy gets a graveyard target that already cantripped. The single life is the entire cost of the draw, and at this point on the curve it is a price most black decks barely notice. What keeps the exchange fair is the body it comes attached to: a 1/1 with no evasion and no relevant combat profile, so the value lives in the enters trigger and whatever the creature does afterward, not in the attack step. This is a replacement-level engine piece that asks nothing of your deck except that you wanted to draw a card anyway, which is why it slots into so many black builds without ever being the reason any of them exist.