This section details the standard Vancian spell system for D&D, giving the basics of how it works. It also specifies that if spellcasting is interrupted in any way - such as the caster being shot by an arrow for instance - the spell is lost. There's a little bit about verbal and somatic components, and the kinds of things that can disrupt them: magical silence, paralysis, being grappled, etc. Gary specifies at the end that any spell being cast in combat requires the player to be ready with his choice when the round begins: any hesitation, and the moment is lost.
There's a short bit about how spell scrolls work. When read the spell disappears, and there's no need for somatic or material components. Spells from scrolls are generally cast at 12th level, although attack spells are apparently a bit more variable. Gary directs the reader to the Dungeon Master's Guide for more info.
In this section, Gary writes about the three main adventuring areas: dungeons, wilderness and cities. There's nothing too revelatory here, just an outline of the basics, and some rudimentary survival tips. The city section probably contains the most interesting stuff. It's mentioned there that "questions about rank, profession, god and alignment are perilous, and the use of an alignment tongue is socially repulsive in most places". There are a lot of setting implications in that short passage.
A brief discussion of encumbrance and movement rates is given. In very general terms, a character carrying about 35# (pounds) of gear can move at 12". One carrying about 70# can move at 9", and one with about 105# can move at 6", and has their reaction time and initiative slowed. Gear over 105# results in a character only being able to move at 3" or 4", and being greatly slowed in reaction time and initiative. It's also mentioned that bulk should factor into these calculations as well, but that's left pretty vague. Strength scores modify these numbers (which wasn't the case in OD&D until the Greyhawk supplement).
We learn that ten coins weigh a pound (which makes for some pretty hefty coins). The weights of items have previously been given in coins, so it's kind of irritating to be working with two different measurements here; I feel like AD&D should stick with one. If I recall correctly, coins are the usual measurement, so I probably don't have to worry about it. I guess it's also handy for when you have to come up with weights for items that aren't in the PHB.
I'm kind of surprised that we're not given anything specific here for how armor affects movement. It's mentioned in passing, but there were no weights given for the various suits of armor in the equipment chapter, as far as I can see. Have I missed something, or will this be delayed until the DMG?
It's interesting to note the differences in how much characters can carry between OD&D and AD&D. If I'm interpreting OD&D correctly, then any character carrying up to 750gp can move as Light Foot (12"). One carrying up to 1,000gp can move as Heavy Foot (9"). One carrying up to 1,500gp moves as Armored Foot (6"). In AD&D, it would seem that 12" movement ends at 350gp, 9" ends at 700gp, and 6" movement ends at 1,050gp. The numbers given for AD&D are much smaller, but it should also be remembered that Strength didn't originally modify encumbrance in OD&D.
MOVEMENT - TIME AND DISTANCE FACTORS
The scale of movement and how it interacts with the passage of time and your surroundings is detailed here. Dungeon movement is tracked in tens of feet per turn, so that a character with a movement rate of 12" will cover 120 feet in ten minutes. This seems ultra-slow, but it assumes mapping and exploring an unfamiliar area. This rate is multiplied by five in familiar areas, and multiplied by ten when fleeing. When the movement rate is so increased, it mentions that each move takes 1/5 or 1/10 of a turn; does this mean that wandering monster checks come more frequently, or does it only affect movement rates? It also mentions that movement rates aren't increased during flight when you're encumbered, which is a little odd, but I guess it motivates fleeing characters to dump whatever treasure they might be loaded down with. What do you do if you're in plate mail though?
Combat movement is converted to tens of feet per minute (so the same pace as when you're fleeing), which is further divided by ten for each segment. Again it seems slow - remember that a round is 1 minute and a segment is 6 seconds - but Gary counters by saying that the character is in a dangerous situation and probably on the defensive.
For outdoor movement, the movement rate is converted to the number of miles the character can cover in half a day. Combat in the wilderness is handled the same as in the dungeon, which surprised me. I thought there'd be a mention of movement outside being converted to tens of yards rather than feet.
In cities, movement is converted to tens of feet per minute. If you're mapping, it reverts to tens of feet per turn (10 minutes), just as in the dungeon. Mapping a city seems like a weird thing to do, though.
There's also a note about mapping being impossible when pursued, and that light is required. You can't map using infravision, either. Is this the first indication that infravision is based on heat? I can't recall for certain. Gary also mentions that some standard maze navigation tricks - such as making marks or leaving a string - are useless, because monsters will come along and destroy them.
The range of illumination is given for various common light sources, although candles are a notable omission. They're on the equipment list, so they really should be here as well. Interestingly, the range of illumination is given for magic daggers, short swords and longswords. Do all of these weapons glow in AD&D if they're magical? What about other magic weapons?
Infravision is described here specifically as "the ability to see radiation in the infra-red spectrum", and it's noted that most monsters and nocturnal animals will have it. It's also mentioned that it's likely that not every member of an adventuring party will have infravision, and so a light source will probably be required.
Further information is given regarding infravision. It detects heat radiation, so that warm objects are bright, cool objects are grey, and cold ones are black. Dungeon dwelling monsters will have an infravision of 120', which is double that which will be possessed by most PCs. Infravision is spoiled by regular light, and sources of great heat. There's also a bit about it being able to pick up thieves that are hiding in shadows. It's logical, but I feel like the poor old thief doesn't need to be hobbled in this fashion.
Creatures with this vision can see into the ultra-violet spectrum (gamma rays and x-rays are specifically mentioned), allowing them to see well at night. Wouldn't this type of vision be more suitable for nocturnal animals than infravision?
Basically, thieves and those with the relevant magic items have the ability to move with complete silence. Anyone else is out of luck - they can move quietly, but not silently. The percentage roll for figuring this out is explained, and it's noted that characters moving silently gain a bonus to surprise rolls.
After a quick mention that cloaks of elvenkind provide invisibility to the area they cover, and that spells provide superior invisibility, it's noted that an invisible character still needs light to see, and that light will be visible to anyone else around as well. Gary's always quick to point out logical stuff like this, especially when it can hose the PCs. I guess it applies equally to monsters, but probably not, because most of them will have infravision.