I was thinking of taking Cloud of Daggers for my Wizard but I can't seem to find a clear answer on what the AoE for the spell is intended to be.
PHB said:You fill the air with spinning daggers in a cube 5 feet on each side, centered on a point you choose within range
DMG said:Choose an intersection of squares or hexes as the point of origin of an area of effect, then follow its rules as normal.
Based on these, I'm imagining this as the spell's AoE:
However, the spell's description states that it is a cube, an AoE mentioned in the PHB.
PHB said:You select a cube’s point of origin, which lies anywhere on a face of the cubic effect. The cube’s size is expressed as the length of each side. A cube’s point of origin is not included in the cube’s area of effect, unless you decide otherwise.
This leads to interpretations that Cloud of Daggers only occupies a single space on a grid. However, this text states that a cube's point of origin is on the face of a cube, whereas the text for Cloud of Daggers states that cube produced by that spell has an origin in its center rather on a face.
Jeremy Crawford, when asked, basically said that the AoE is either one space or four spaces, whichever your DM prefers.
Crawford has also said that, save for AoEs that are circular, any space that an AoE covers to any degree is considered to be effected.
Compare to the cantrip Create Bonfire:
You create a bonfire on ground that you can see within range. Until the spell ends, the magic bonfire fills a 5-foot cube.
The wording here omits the game concept of a point as its origin, so it's clearer to me that only a single grid space would be affected. Plus it's a cantrip and not a 2nd-level spell, so a single space feels much more appropriate for an AOE.
I'm curious to see what the general consensus here is. Personally, I feel that the spell description for Cloud of Daggers contradicts the rules for cubic AoEs so much that it would be better written as a spherical AoE.
EDIT: I'm fairly confident now that Cloud of Daggers is supposed to be an AoE that can affect four squares but also does not fill them, so creatures can squeeze past unharmed but are hurt if they walk into it normally or are pushed in. No other AoE spell is like this, but no other AoE spell is described as a cube centered on a point (as far as I'm aware).