Help needed

[KaNT]

I have an encounter in mind for my party, that is going to involve 9 enemies standing together in a 3x3 grid formation, each of them with an effect up that causes 1d4+2 points of damage to everything of a certain type in a 20 foot radius. Those stack, and I am having a heck of a time drawing out the pattern for my battle map. Every time I try to figure out where the party is going to take what damage, my brain takes a vacation.

What squares are they going to be taking only 1d4+2, what squares are they going to be taking 9d4+18, and eveything inbetween.

[Galvin]

Think of it like a Ven Diagram. The entire area will resemble a 40x40 square, more or less, and just place each square within the Ven Diagram. It would help if you were to draw the Diagram on the paper.

[Humble Master]

Think of it like a Ven Diagram. The entire area will resemble a 40x40 square, more or less, and just place each square within the Ven Diagram. It would help if you were to draw the Diagram on the paper. I would second this. Get some graph paper and draw the 9 creatures. Then trace the 20ft circle around each of them. Any good graphing calculator would be able to do a similar job.

[Asrrin]

I'm sitting here trying to figure it out for this poor guy and I realized I don't have a firm grasp on where to start and end line of effect.

Does the source originate from the center of the square they occupy?
If not, does it originate from a corner of the square it occupies? If so, which corner? Any corner? All corners?
How much of a square needs to be "in" the field of effect in order for it to count?

In any case, no matter how the math works out, I can say for certain all adjacent squares to the formation should receive the full 9 stacks.

EDIT: OK, I found this (http://www.d20srd.org/srd/magicOverview/spellDescriptions.htm#area) that explains how to target it, and boy it's still going to be a mess.

EDIT #2: Wow, this is turning out to be a big mess and there is no simple way I know of to plot this all out short of brute forcing it. I'm asking some math-inclined friends of mine if they have any clues, but for simplicities sake I'd just rule the following:

20ft. from nearest source: 1 stack.
15ft: 4 stacks
10ft: 7 stacks
5ft: 9 stacks.

This seems to be true anyways for all but the weird squares that are in between diagonals and such.