Changes to the d20 mechanic to fit the Moldvay Basic style

This is Part 1 of an ongoing series - the introduction and table of contents can be found here.

In order to bend the D&D Third Edition rules into the tiny box that holds my re-imagined Moldvay Basic, the biggest change is probably going to be to the core d20 mechanic. There will be other changes, but this one will affect the way attacks, skill checks, and saving throws are handled so it's probably the most important.

For the solution, I propose this set of AC/DC (for Armor Class/Difficulty Class) tables. Will they work? I have no idea. The idea is to provide one table for characters and their associated NPCs, and another for "monsters" (which is the game definition of any NPC not under the control of the players).

Here's the table for the Characters to use:

Character	AC / DC
Level	11	12	13	14	15	16	17	18	19	20	21	22	23
Normal Man	11	12	13	14	15	16	17	18	19	20	20	20	20
1st-3rd	10	11	12	13	14	15	16	17	18	19	20	20	20
4th +	08	09	10	11	12	13	14	15	16	17	18	19	20

Any time a character or one of their NPCs makes an attack, needs to make a save, or to do something that you deem requires a roll, you consult this table and look up the appropriate number along the top to find the result. One could adjust the table to cover AC 10-20, or expand it higher if you want high level DCs -- I based this table straight off the Moldvay Character Attacks table on page B27. It's not groundbreaking, but remember that all characters use this table, regardless of class. Later on I will talk about using feats or class abilities to modify this, but this is the core combat/save/skill check engine.

Now, for monsters, it's going to be more involved. Even though we're limiting characters to only two stages of advancement (or three if you count their NPCs) Monsters can have 17 hit dice or more. Of course, if you want a really gritty game with lots of rolling you can use the Character AC/DC table, but let's look at how the Monster AC/DC table looks:

Monster's	AC \ DC
Hit Dice	11	12	13	14	15	16	17	18	19	20	21	22	23
Up to 1	10	11	12	13	14	15	16	17	18	19	20	20	20
1+ to 2	09	10	11	12	13	14	15	16	17	18	19	20	20
2+ to 3	08	09	10	11	12	13	14	15	16	17	18	19	20
3+ to 4	07	08	09	10	11	12	13	14	15	16	17	18	19
4+ to 5	06	07	08	09	10	11	12	13	14	15	16	17	18
5+ to 6	05	06	07	08	09	10	11	12	13	14	15	16	17
6+ to 7	04	05	06	07	08	09	10	11	12	13	14	15	16
7+ to 9	03	04	05	06	07	08	09	10	11	12	13	14	15
9+ to 11	02	03	04	05	06	07	08	09	10	11	12	13	14
11+ to 13	02	02	03	04	05	06	07	08	09	10	11	12	13
13+ to 15	02	02	02	03	04	05	06	07	08	09	10	11	12
15+ to 17	02	02	02	02	03	04	05	06	07	08	09	10	11
17+ or more	02	02	02	02	02	03	04	05	06	07	08	09	10

No surprises here, though I never noticed the 2-HD bump beginning with monsters who had 7+ HD. I suppose if you wanted to have an "overpowered" Basic-style game you could use this table for characters, but I rather like the fact that a 10th level Fighter is going to be significantly outmatched in terms of to-hit capability when compared to a 10 HD monster.

Now, I am assuming with this system that we will use the standard 3E trio of saves - Fortitude, Reflex, and Will, along with the character bonuses to those saves based on level and a target DC. Maybe you prefer the increased granularity of the old save system, and/or you prefer to not have your character's saves increase, beyond a +2 bump at 4th level, and you don't want to use DCs? Let's see how an adapted Saving Throw table might look:

	DC for Type of Attack
Character	Death Ray	Magic	Paralysis or	Dragon	Rods,
Class	or Poison	Wands	Turn to Stone	Breath	Staves, or Spells
Normal Man	14	15	16	17	17
Cleric	11	12	14	16	15
Fighter	12	13	14	15	16
Rogue	13	14	13	16	15
Sorcerer/Wizard	13	14	13	16	15
Dwarf/Halfing*	10	11	12	13	14
Elf*	12	13	13	15	15

The asterisks next to the Dwarf/Halfling and Elf entries are if you are aiming for a race-as-class style game.

This table should be pretty straightforward - the number is the DC that the character will need to meet or exceed in order to save against the particular hazard. Just be sure to use the correct level (1-3, or 4+) if you use this. It doesn't exactly line up with the old table (you would just use the number above as the target rather than the DC if you wanted that) found on B26, but it still reflects the variety of saves for each class and improves with the jump at 4th level. If you just use the old table as-is, characters of level 4+ gain a +2 bonus to their saving throw rolls.

I will talk more about classes in a later installment, but clearly most of the 13 classes in the Third Edition player's handbook aren't directly represented above. One question about using the five-fold saves above is whether it would be better to consolidate the classes, a'la Advanced Dungeons & Dragons (i.e., Fighters, Paladins, and Rangers all use the Fighter entry), or to expand them. For me, I'll just use the 3E-style saves but I thought it would be interesting to look at the old system and think how to adapt a newer system to use the old saves.

That's it for this installment - In my next installment I'll look at characters - races, classes, abilities, and so forth.