RPG Week: D&D Rules Cyclopedia Day Four

Let’s talk combat. In the world of Classic D&D there’s hardly a mention of miniatures, battlemats, squares or other such economically-driven ephemera to be found in recent D&D. This is pure in-your-head gaming of the first degree where the action is driven by your imagination and narrative Powers instead of at-will, encounter or daily Powers.

This is combat, unchained. The players are free to do anything they want, as often as they want provided it’s in keeping with the character and dramatically appropriate. Want to shove that Ogre off a cliff? Go for it, and make a roll. There’s no looking down your character sheet to see if you’ve any Powers that will Shift your foe the required number of squares – you just do it! This is D&D freed from the constraints of the game designer’s minds where the GM and the narrative is king. Talk to us grognards about the Best Combats Ever and you’ll hear wild tales of Magic-Users casting Fireball to light an army’s arrows, Fighters leaping underneath a giant and castrating him with his greatsword, and Rogues dropping from ceilings firing off paired Crossbow Pistols into a room of Goblin Horsethiefs. It’s a version of D&D that provides just enough rules to play, but encourages the gamers to used them in wild and unpredictable ways – and garner the XP for quality play.

On to the mechanics.

Classic D&D provides three mathematically equal ways to see whether you’ve hit a foe. Option One is look the result up on a bigass table, cross-referencing your Class/Level against your foe’s AC. Roll d20, add any modifiers and if you get equal or higher than number from the table, you’ve hit. As your level changes infrequently, it’s common just to jot the relevant line down on your character sheet for quick reference.

For example, a 6th level Thief’s sheet would contain the line:


AC   10 9 8  7  6  5  4  3  2  1  0 -1 -2
Roll  7 8 9 10 11 12 13 14 15 16 17 18 19


As GM, I could just tell the players the opponent’s AC, and they all know what they need to roll on a d20. We also granted max damage on a natural 20 – something echoed in 4e’s Critical rules.

That’s Option One. The second choice is to use the much maligned THAC0. This is just the math of the table, brought to the gaming…. errrr… table. Note down the number required To Hit AC0 (THAC0 – see?), and just take the AC the GM gives you from that to get the number you need to roll to hit. For example, the Thief above has THAC0 17. If she’s fighting against an AC 4 foe, he needs (17-4) = 13 or more to hit. Check it against the table above – it works! The math falls apart a little against negative AC foes where (as per the table) the “20” result is duplicated a few times, but generally speaking we just stuck to this method of rolling and didn’t worry about that discrepancy.

The third choice is to twist the THAC0 math around a little more. Roll d20 and take that result away from your THAC0; that’s the highest AC you’ve hit. In the example above, if our Thief rolls a 12, then he’s hit anything with (17-12) = AC 5 or worse. That AC 4 foe had ducked the blow!

A wise GM used both THAC0 methods, with the players using Option Two for their characters, and the monsters using Option Three. This put all the working out of who-hit-what onto the players, so you (as GM) just have to roll the dice and can concentrate on describing the action. The only annoyance with the Rules Cyclopedia is that the Monster entries don’t contain their THAC0 (which is derived from Hit Dice), so in my copy I went through and added them all in by hand.

But, as they say, that’s not all! Close combat is just a tiny part of the battle rules inside the Rules Cyclopedia. There’s unarmed combat, wresting, naval, underwater and aerial combat, siege warfare and huge-scale mass battles – and that’s what I’m going to talk about, next time.

See you there!