It's a fantasy role-playing game.

DM: You are Jester Lavorre, a tiefling cleric . You are the member of the famous group of adventurers. Previously, Nott and you, to almost universal horror, break out Fluffernutter, with you throwing the barrel in the air towards the heads, but Nott's explosive bolt misses and the barrel splashes into the water. Just prior to Yasha's turns, Caduceus casts Path to the Grave on the hydra, making it vulnerable to everything for double damage.
DM: No, it just says, you create it for a minute, it says it's concentration, an unoccupied space, you can move the illusion for 30 feet in space you can see, but it must remain within 120 feet of you.
Player: Okay, then--
DM: But you cannot see any of these spaces where it is.
Player: Oh, can I move around the corner? Then see it?
DM: You can. Right now it's consumed in darkness. You cannot see anything past this. The Hunger of Hadar is blocking all your vision. You do not know where your illusion is, you just see this large sphere of darkness.
Player: I can't move it at all?
DM: Correct.
