Spell Definitions


In 3rd Edition, fireballs instantaneously create a 20' radius sphere of effect which affects everything within it. It exerts very little pressure, and the area is always a perfect sphere, though areas within that sphere may be protected by obstructions such as walls. It may or may not burst doors etc., depending on how much damage it does to them.

Back in the olden days, the burst of a fireball was represented as a ball of flame, which expanded to a set volume and conformed to its surroundings. That meant that if you cast a fireball is restricted surroundings (such as an underground passage) you were quite likely to wear a "blow-back", and be the subject of dark looks and bitter jibes from all of your unfortunate companions, assuming they survived.

I like the old way of handling fireballs, so we will be reverting to it.

To do that we need to know what the volume of a 20' radius sphere is. If I recall correctly, the formula is something like 4/3 πR3, so that would give us a total volume of 33510.3216299135474673620807857476 feet3, which is the equivalent of 268.08257303930837973889664628592 5-foot cubes.

I think perhaps rounding down to 250 five-foot cubes might be a good idea. That will completely fill a corridor 2 hexes by 2 hexes by 62 hexes long, or a chamber 10 hexes by 7 hexes by 3.5 hexes high.

What all this means in practice is that you really ought to be careful where you're tossing fireballs around, just in case the DM is feeling particularly vindictive. This is where a handy program to map the fireball's spread would be useful. Until I can convince some fool to write one for me, I guess it'll just have to be done manually :)