Selling your Soul at a Premium: The Warlock's Guide to Power

[Millstone85]

it is short range

Right where you need a cantrip without an attack roll (or with a melee one).

does absolutely nothing on a passed save

Is there a cantrip that does?

Poison is the most resisted damage type in the game with also the most creatures immune to it.

the save is based on an attribute that most enemies will be at least somewhat good at.

Ah, okay. Since I have no idea how the DM does his monster cuisine, I tend to select things on the assumption that we will be fighting humans.