Call Lightning says that you pick a point for lightning to strike, and each creature "within 5 feet of that point" are affected by the strike. What does that mean?
I'm tempted to read it as only affecting a single 5-foot square, but the wording suggest that it is intended to be an AOE attack (unless it's accounting for the very rare occasion of two creatures sharing a space).
So, when using a standard grid, does the caster pick a square, and then all adjacent squares are affected? If so, why not say it affects a 15-foot cube centered on the target-point? (I guess the spell effect section doesn't describe square areas, just cube areas).
Similarly, does Arms of Hadar affect 10 squares from the caster in every direction? (so, ultimately a 50-foot square area)