The dazed substantiation in 5e dnd Hunger of Hadar comes from the magical darkness. Meaning true sight, which explicitly states the critter can see through magical darkness, would give vision into, out of, or within the area of effect. It was a conjuration spell for witches that used the power of Hadar, the Dark Hunger, a Far Realm- overran star that was within Realmspace. You open a gateway to the darkness between the stars, a region agonized with unknown horrors. A 20- bottom- compass sphere of ambiguity and bitter deep freeze appears, concentrated on a point with range and lasting for the span. This void fills with harsh whispers and belting noises that could be heard up to 30 bases down. No light, magical or else, can illuminate the area, and brutes entirely within point are dazed.