Mapless D&D Combat, part 1

I'm considering getting rid of the battlemat and figures for my next d20 campaign. The main disadvantage in doing so is that several sections of the rules are designed for to allow for tactical advantages based upon positioning. In this post I'll tackle Area Effects in abstract combat. I'm saving the whole AoO's and Flanking for a future date. But first, how many orcs does my fireball hit?

FOES AFFECTED BY AREA ATTACKS

AREA	SPARSE	AVERAGE	CROWDED	vs. PCs
5' radius	d4	d3+1	d2+2	d2
10' radius	d8	d6+2	d4+4	d3
15' radius	d20*	d12+12	d6+18	d4
20' radius	d30	d20+24	d10+34	d6
15' cone	d6	d4+2	d3+3	d3
30' cone	d20*	d12+12	d6+18	d6

*Substitute a d24 if one is available.

Adjust the number rolled based upon foe size. For example, double the number affected if the foes are small and divide the number rolled by 4 for large numbers.

At the DM option specifying a particular target in a group ('I center the effect on the wizard') bump the dice range one category to the left. Crowded groups are treated as average density and average groups as sparse. Half the numbers rolled for sparse groups.

The special 'vs PCs' column is designed to take into account that most players are smart enough to avoid crowding up against a dragon or fireball-lobber. A DM could probably get away with occasionally using this column for tactically-minded NPC groups.