Except the game uses Chebyshev distance, so as long as they’re within 30 feet in the x, y, and z dimensions, they’re within 30 feet.
Though for area damage spells, it’s much, much more complicated. You don’t just have to find the Euclidean distance from them to the center. You have to calculate how much of their square is within that distance.
Except the game uses Chebyshev distance, so as long as they’re within 30 feet in the x, y, and z dimensions, they’re within 30 feet.
Though for area damage spells, it’s much, much more complicated. You don’t just have to find the Euclidean distance from them to the center. You have to calculate how much of their square is within that distance.
That’s an optional variant rule described in Xanathar’s Guide. The default rule for grids is simpler: just do Chebyshev.