I have a question regarding how a Hallow spell affects a T1 party. The most obvious interaction would seem to be blocking familiars since they are fey, fiend, or celestial.
Does the Hallow spell with all of its potential creature types designated stop familiars from entering the area? Does it stop them from being summoned in there? Stop them from being brought out of demiplane into it? Do any of those answers change when it has the additional extra-dimensional interference effect?