I was recently in a situation where I had to make a crossbow attack on an enemy that is in the opposite corner of the room from where I was.
It looked a bit like this:
For the sake of simplicity, let's assume my weapon has a range of 25 feet, and that each square is 5 feet wide.
If I count the diagonal squares, the enemy would just be in range. But if I calculate it mathematically with Pythagoras' theorem, the enemy would be 35 feet away, and thus not be in range.
The PHB only states about the Range weapon property:
Range. A weapon that can be used to make a ranged attack has a range shown in parentheses after the ammunition or thrown property. The range lists two numbers. The first is the weapon's normal range in feet, and the second indicates the weapon's long range. When attacking a target beyond normal range, you have disadvantage on the attack roll. You can't attack a target beyond the weapon's long range.
I know there is a rule for diagonal movement where your first diagonal square costs 5 feet, the second 10 feet, and so on... I don't know where this rule is written, I just heard it somewhere.
How is the range of an attack determined, by RAW?
- Just count the squares?
- Calculate the diagonal, which would amount to 7 feet for each square?
- Use the movement rules?