Hallow states “Celestials, Elementals, fey, Fiends, and Undead can’t enter the area…” but it doesn’t say what would happen if someone tried to summon some into the area. Would the spell fail? Would the elementals appear but then be forced to leave?
Would the ruling be the same for both Conjure Minor Elementals and Conjure Elemental? The latter uses a source of the element (e.g. a fire, what if the fire is in the Hallow area?) while the former just makes some minor elementals appear from an unspecified source.
When discussing ways to take down Count Strahd von Zarovich in my CoS campaign, my players considered casting the Hallow spell and covering literally all of Barovia in hallowed ground. They figured they can do this because of the text of the spell (PHB Page 249):
You touch a point and infuse an area around it with holy (or unholy) power. The area can have a radius up to 60 feet, and the spell fails if the radius includes an area already under the effect of the hallow spell.
(Emphasis Mine, 6th Printing of PHB)
So because of how the spell is written, there is no shape defined. Maybe sphere is implied by the use of a radius, but they also figured they could simply opt for a smaller cube shape that would fit within that sphere, because it is not explicitly defined. With that in mind, they will not have any overlapping because you can fit cubes together perfectly. Looking at the Areas of Effect on pages 204 and 205 we can see that Sphere says this:
You select a sphere’s point of origin, and the sphere extends outward from that point. The sphere’s size is expressed as a radius in feet that extends from the point.
As far as I (and one of my players helping me research this) have found, every spell that expresses that it is a sphere whether or not it gives you a specific radius or says “up to [some] radius.” It could simply be a circle, but there needs to be a three-dimensional area that it affects, so that is the same as making it a limitless cylinder.
So is it actually a Sphere or is it just some shape that fits within the boundaries?
When using the fear extra effect of the hallow spell, the spell says that affected creatures are frightened whilst in the spell’s area.
With regards to the frightened condition, is the source of fear the point at which hallow was cast or the whole area?
This matters for how it interacts with both parts of the frightened condition.
If the source of fear is the point at which the spell is cast, then affected creatures can move away from it and there might be ways to break line of sight within the hallowed area itself.
If the source of the fear is the whole area, being inside the area means that the source of fear is in all directions from the affected creature. This would mean that the creature could not willingly move in any direction, as all directions would be closer to the source of fear. (Alternatively you could interpret it as you are always at the source of fear so you could freely move as moving in any direction could not put you closer to the source of fear than you already are.) In addition to the movement restriction/non-restriction (depending on your interpretation), the whole area being the source of fear would mean you are always subject to the effect of being in line of sight of your source of fear whilst in the area.
What is the correct interpretation?
The paladin’s Divine Sense feature allows the paladin to
…detect the presence of any place or object that has been consecrated or desecrated, as with the hallow spell.
Similarly, the spell detect evil and good allows the caster to
…know if there is a place or object within 30 feet of you that has been magically consecrated or desecrated.
How, other than via the spell hallow, can a place or object be consecrated or desecrated, so that it would be detected by Divine Sense or detect evil and good?
Question inspired by this one from earlier today, where we establish that Divine Sense cannot detect whether an object is cursed.