There are 24 4th-level magic-user spells in AD&D, up from 16 in OD&D (all of which made the transition at the same level). Of the eight spells unaccounted for, all are brand new except for fire trap, which was previously presented in the PHB as a druid spell.
Charm Monster: Like charm person, but can affect any living creature. The target will regard the caster as a friend and follow reasonable requests, but has a percentage chance every week of breaking free (with a higher percentage based on the creature's level/HD). Multiple creatures of 1 to 3 HD can be affected, but at 4 or above it only works on one target.
The OD&D version affected all creatures, with no stated requirement that they must be living. The number of creatures of 3 HD or lower affected was determined on 3d6, which is much higher than the AD&D numbers (which allow for 8 at most). In general, creatures in OD&D had a smaller percentage chance of breaking the spell.
Confusion: This spell functions like the 7th-level druid spell, but with a higher range (12" compared to the druid's 8"), a slightly longer duration (2 rounds + 1 round/level as opposed to 1 round/level), a larger area (6" x 6", as opposed to the druid's 4" x 4") and a quicker casting time (4 segments, compared to 9). It also affects a base number of 4-16 creatures, whereas the druid spell only affects 2-8; this number can be modified upwards if the strongest creature affected is of lower level than the caster. Every creature affected will take a random action: wander away for 1 turn, stand confused for 1 round, attack the nearest creature for 1 round, or attack the druid and his allies for 1 round. Its material component is three nut shells.
The OD&D spell automatically affected creatures of 2 HD or less, and had a delayed effect against higher-level targets (based on a d12 roll minus the caster's level). Only creatures of 4 HD or more got a saving throw against it. There was no option for the targets to wander away, and a higher level caster got a bonus to the random roll, to influence the confused targets away from attacking the caster's allies. It had a duration of 12 turns (much higher than that I detailed above for AD&D) and a range of 12" (which has been unchanged).
Dig: Creates a 5' x 5' hole that is 5' deep per caster level. Holes deeper than 5' have a chance to collapse (15% per extra 5'), and that chance is even greater in sand and mud. Creatures caught in the middle of the pit when it's created will fall in, and those at the side must make a saving throw (against their Dexterity score, which is an unusual one in AD&D) to avoid it, as must anyone caught moving rapidly towards it. The material components are a small shovel and bucket which the caster must hold while the pits are excavated (which confirms that multiple pits can be created during the spell's duration).
Dimension Door: Teleports the caster 3" per level. There's no error in the teleportation: the caster lands exactly where he desires. There's still danger, though, because if that area is inside solid matter the caster will be trapped in the Astral Plane, with the only way out being rescue by some other creature. There's also falling damage to consider if the caster appears in mid-air. The caster can teleport with his gear, to a maximum weight of 5,000gp. He can also take living matter to half that weight, so I guess you could pick up another party member and take them along. It takes the caster 7 segments to recover from using the spell, though it's not clear what exactly this entails; possibly that they can take no actions, or are easier to hit?
In OD&D the spell teleported an "object" up to 36" with no error. The range was, of course, much greater than in AD&D, but the big difference was that the spell could be cast on another person or thing. In AD&D, it's limited to the caster. There was also nothing about being caught in the Astral Plane, or recovery time.
Enchanted Weapon: Makes a weapon effectively +1, although it doesn't actually confer that bonus. It just means that the weapon can affect monsters that are only hit by magic weapons. It affects one large weapon, or two small, but missile weapons lose the enchantment after being used. Everything else lasts for 5 rounds/level. The material component is powdered lime and carbon.
It's a useful spell, but only in very specific circumstances. Most parties with access to this spell will be loaded down with +1 weapons, and your average 7th-8th level magic-user probably has better attack options than this. It's perhaps more useful in scroll form for low-level parties.
Extension I: This spell can be used to extend the duration of a previously cast spell of 1st-3rd level by 50%. It's said to only work on spells where duration is meaningful, which almost certainly rules out making a fireball burn for longer. The OD&D version of the spell was exactly the same.
Fear: All creatures caught within a 6" long cone must make a saving throw or flee from the caster at top speed. There's also a chance they'll drop any items being held (60% for 1st-level targets, modified down by 5% per level higher than 1st). The material component is the heart of a hen or a white feather.
The OD&D spell worked similarly, but targets had a flat 50% chance to drop what they were carrying, unmodified by level. The duration was 6 turns, whereas in AD&D targets will run for a number of rounds equal to the caster's level. The spell had a range of 24", while the AD&D spell only goes to 6". The OD&D spell functioned like the fear wand, though, so it's still a 6" cone. Does this mean that OD&D casters could designate the beginning of the cone anywhere within 24"? It feels a little odd, but I guess it's not that different from lightning bolt. The AD&D spell almost certainly originates from the caster.
Fire Charm: The caster causes a normal fire to be surrounded by a 'gossamer veil of multi-hued flame'. Any creatures observing the flame must save vs. magic or be forced to stand transfixed. While in this state, they are subject to a suggestion of 12 or fewer words (saved against at a -3 penalty). The trance will be broken by an attack, an object passing between a victim and the flame, or the end of the spell. The material component is a super-thin piece of silk that must be thrown on the fire. This is a new spell that fills an important niche: a mid-level charm spell that can work on a large crowd. There's mass charm, but it's so high-level as to be inaccessible in most games, and has a Hit Dice restriction that limits the number of creatures that can be affected.
Fire Shield: Appearing surprisingly for the first time, this one was often the bane of my existence when playing the Gold Box CRPGs. It surrounds the caster with a wreath of flame with two possible variations. The blue-green flame protects against cold spells, but makes the caster more vulnerable to fire. The blue-violet flame protects against fire, but makes the caster more vulnerable to cold. Those aren't the most irritating effects, though. What it also does is damage anyone who hits the caster in melee: the caster takes normal damage, but the attacker takes that same damage doubled, which is a real kick in the balls for a fighter with 18/00 Strength, or a girdle of giant strength. The upside is that it only works on the caster, and magic-users have low hit points. If it could be cast on stronger targets, it would be a game-breaker.
Fire Trap: This spell is new to the PHB, but it appeared earlier as a druid spell. It can be cast on any object that can be opened. The caster can open the item safely, but anyone else will discharge the trap, a 5' radius explosion which deals 1d4 damage +1 per caster level (save for half). This explosion doesn't harm the object of the fire trap. It's also twice as hard to detect as other traps (the regular chance is halved) and any failure to disarm it will set it off.
There's a lot of business about how the spell interacts with hold portal, wizard lock and knock spells. If an item has hold portal and fire trap cast on it, only the first spell cast will work (and both are negated if they're cast simultaneously). Wizard lock is a little more complicated. A fire trap cast after a wizard lock will negate the fire trap. Simultaneous casting will negate both. If the fire trap is cast before the wizard lock there's a 50% chance for both to be negated. Nothing is said about what happens otherwise, but the implication is that both spells will be in effect. As for knock, it has no effect at all on a fire trap spell.
For the material component, the caster must "trace the outline of the closure" with a bit of sulphur or saltpeter. Does that powder have to remain in place, or can it be swept up after the spell is cast? Probably the latter. Besides, there are certainly objects which will be moved around after the spell is in place.
I'm often struck by just how little damage a lot of AD&D spell deal. Seriously - 1d4, +1/level? Is it really as ineffectual as I think, or have I just been corrupted by the numbers bloat of 2nd and 3rd Edition?
Fumble: Makes one target super-clumsy for 1 round/level. The target will fall whenever they try to run, and will drop any item held. Recovery from these takes about a round. Even creatures that make their saving throw are affected as if by a slow spell, so this is actually a great spell for reducing the effectiveness of a single powerful foe. It's material component is a dab of solidified milk fat.
Hallucinatory Terrain: With this spell you can change the appearance of wilderness terrain, such as making a pond look like a grassy field. It persists until hit with a dispel magic or touched by an intelligent creature. It's material components are a stone, a twig and a bit of green plant. My main concern with this spell is the area: it affects a 1" square per caster level, which just seems too small for a lot of the effects you might want to use it for. There's also the definition of "terrain" to be considered. As written it seems as though it's meant for use in the wilderness, but there's nothing stopping it from being used indoors, or in a dungeon.
The OD&D spell is similar, if a bit more vaguely worded. It doesn't have a specific area of effect, it's simply said that it affects a "large area". It had a range of 24", whereas AD&D has as range of 2"/level.
Ice Storm: As usually cast, it creates a storm of hail stones in a 4" diameter that cause 3d10 points of damage (with no saving throw). It can also create sleet in an 8" diameter, which I've never seen used: this blinds all creatures within, and makes the ground icy, reducing movement by 50% and causing anyone who tries to move to slip half the time. Its material component is a pinch of dust and a few drops of water.
The OD&D version doesn't have the sleet option, and affects a 3" cube. It had a duration of 1 turn, but that's undoubtedly a case of OD&D mixing up its turn/round terminology. It had a flat range of 12", whereas AD&D has a range of 1"/level.
Massmorph: With this spell, 10 man-sized creatures per caster level can be made to appear as trees. They can be passed through or touched without revealing their true nature, but wounding them will do so (because the trees bleed, which is a neat touch). The spell persists until hit with dispel magic, or dismissed by the caster, but what happens when the creatures attack? Do they still look like trees as long as they're within the area of effect? Speaking of the area, it's said to be 11' x 1" square/level. The 1" square/level I get, but that 11' sticks out. Is that the height?
The OD&D version of the spell affects up to 100 man-sized creatures, which sounds great but will eventually be surpassed by AD&D casters. It had a range of 24" (it's 1"/level in AD&D) and no stated area of effect.
Minor Globe of Invulnerability: Creates a 1" diameter globe around the caster that completely blocks all 1st-3rd level spells. The one exception to this is dispel magic, which can take the globe down. The caster inside the globe can fire whatever spells he likes out of it, without affecting the globe at all. The material component is a glass or crystal bead. It's an essential part of the magic-user's buffing arsenal, and I'm surprised to see it entering the game so late.
Monster Summoning II: Works like monster summoning I, but summons 4-6 monsters of 2nd-level. With no DMG out at this point for guidance, I'll go to the OD&D dungeon encounter charts to see what sort of things might appear: mostly it's a lot of humanoids (hobgoblins, bugbears and gnolls), some undead (zombies, ghouls), and a few weird monsters (giant ants, giant toads, carrion crawlers). There's certainly a lot of variations in power level here: summoning 6 carrion crawlers could end just about any threat with the right dice rolls.
In OD&D the number of monsters summoned was limited to 1 or 2.
Plant Growth: Works exactly like the druid spell, in that it causes vegetation to grow to form a barrier that is difficult to penetrate. The magic-user version has a duration of 1"/level (druids get a flat 16"), an area of effect of 1" x 1" (druids get 2" x 2") and a casting time of 4 segments (druids take a full round).
The OD&D version of the spell affected up to 30 square inches, and had a range of 12", a much more powerful spell.
Polymorph Other: This is one of the more problematic spells in D&D's history, and it fittingly has one of the longest entries in the PHB. It transforms one creature into any other type of creature that the caster desires. Apparently a creature can't be polymorphed into something with a higher intelligence than its original form, but the later examples seem to put a lie to that: one shows an orc being transformed into a white dragon, and another shows a human fighter being changed into a blue dragon. (Actually, I might be wrong here. Orcs and white dragons both have an Int of Average (low). Blue dragons are listed as Very Intelligent, but there's no reason a fighter couldn't match that.)
The polymorphed creature gets all of the abilities of the creature, but must pass a system shock roll to survive. There's also a chance that the creature will take on the mentality and outlook of their new form: it starts at 100%, and is brought down by 5% for every point of Intelligence. The difference in Hit Dice between the two forms also modifies this roll, making it harder to pass if you're put in a stronger form. This roll is made every day, so it's inevitable that the polymorphed creature will eventually succumb, but before then they can still use all of the abilities of their former body as well. There's also an implication that the target retains its old hit points: the example of a brontosaurus changed into an ant being impossible to squash is given. It's not clear if this works in reverse (i.e., an ant changed into a brontosaurus having only 1 hp). The spell is permanent, and can only be broken by a dispel magic. The material component of this spell is a caterpillar cocoon.
The OD&D version of the spell didn't require a system shock roll, and had nothing about the target eventually losing their minds to the new form. It had a range of 6", whereas in AD&D it's 1/2" per level. Basically, it was an amazing spell with no drawbacks whatsoever.
Polymorph Self: The caster can assume a form from "as small as a wren to as large as a hippopotamus". It doesn't grant any of the new creature's special attacks or defenses, but it does grant their forms of movement (such as flight, swimming, sliding under doors, etc.). There's no risk of system shock, though, and no chance of taking on the mentality of the new form. The caster can change their form as many times as they want during the spell's duration, with each change requiring 5 segments. Upon returning to their normal form, the caster restores 1d12 hit points if they were damaged while polymorphed.
The OD&D spell says that the caster can turn into anything, though it seems that the intention here is for living creatures and not rocks or doors or a nuclear missile. It had a duration of 6 turns + 1 turn per caster level (AD&D has a duration of 2 turns/level). There was no mention of healing when returning to original form, but otherwise the spell is the same.
Rary's Mnemonic Enhancer: Allows the caster to retain the memory of a number of spells equal to three spell levels. So that would be three 1st-level spells, a 1st and a 2nd, or one of 3rd-level. It can be used to instantly memorise those spells, or to retain a spell just cast. Its material components are a piece of string, an ivory plaque worth 100gp, and ink made of squid secretion and either the blood of a black dragon or the digestive juice of a giant slug, all of which disappear when cast. It's a handy spell to have, but that 100gp expenditure every time would make me reluctant to ever bother.
This is the first in-game appearance of Rary, a magic-user played quite early on in the game's history by Brian Blume. Apparently he played the character until 3rd level, when he could then be introduced as 'Medium Rary', then retired the character altogether. There are a lot of later developments in TSR's Greyhawk history, wherein Rary becomes a powerful archmage, but these two accounts don't have to be mutually exclusive. Either Rary went on adventures outside the confines of Greyhawk Castle, or he gained his levels through study (which is probably not allowable by the rules, but something I'm fine with as long as it takes a lot of time and exorbitant amounts of money).
Remove Curse: This spell works exactly like the 3rd-level cleric spell, with the only difference being that the casting time is 4 segments instead of 6. It will remove any curse. Though it doesn't permanently remove a curse from a magic item, it does allow a character with a cursed item to get rid of it. The spell can also be reversed as bestow curse, which afflicts the target with a random effect: reduce an ability score to 3 (50%); -4 penalty to hit and saves (25%); or drop items half the time (25%).
The OD&D version of this spell could remove any curse, and turn a cursed item into a normal item. It wasn't reversible.
Wall of Fire: This is the same as the 5th-level druid spell, except that it has a range of 6" (druids have 8"), and a casting time of 4 segments (druids take 7 segments). The fire created by a magic-user is reddish or violet blue, which is different from the yellow-green or amber fire summoned by druids. It inflicts 2-12 damage +1 per caster level to any creature passing through (2-16 +1/lvl for druids).
Now we need to do some interpretation: the druid spell deals 2-8 damage to creatures within 1", and 1-4 damage to those within 2". Nothing is said about these being different for magic-users, but it stands to reason that if the base damage for passing through the wall is altered, then so should the damage for standing nearby. I would have the magic-user spell deal 1-6 damage to those within 1" and 1-3 damage to those within 2", which is roughly proportionate to how it works for druids. Whatever the damage, only the side facing away from the caster radiates heat. Creatures susceptible to fire may take more damage, and undead always take double.
The spell lasts for as long as the caster concentrates on it, or for 1 round per level. The area of effect is either a sheet of fire up to 2" square per caster level, or a ring with a radius of up to 1" plus 0.25" per level. The sheet is stationary, but the ring can move with the caster. The material component is some phosphorus.
The OD&D version of the spell ends as soon as the caster stops concentrating on it. Creatures of under 4 HD can't pass through at all, and any other creatures takes 1d6 damage. It's still doubled for undead. The spell can still be a wall or a ring; the wall can be up to 6" wide, and the ring is always 3" in diameter.
Wall of Ice: Creates a wall of ice that is one inch thick per caster level, and covers an area of 1" square per level. The length and height can be decided by the caster, as long as it's within the area limit. Creatures breaking through the ice take 2 points of damage per inch of thickness; fire-using creatures take more, and cold-using creatures take less. The wall can be created to fall on creatures underneath, and in that case it works like an ice storm. Strong magical fire will melt the wall in 1 round (resulting in a cloud of fog that lasts for a turn), but regular fire and smaller magical fire has no effect. The material component is a piece of quartz or rock crystal.
The OD&D spell was always 6 inches thick, up to 6" long and 2" high. It's said to "negate the effect of creatures employing fire and/or fire spells", which seems to be pretty much the opposite to how the AD&D spell works. It could only be broken through by a creature of 4 Hit Dice or more, and doing so resulted in 1d6 damage (doubled for fire-using creatures). There was nothing about using the wall to crush your foes, and nothing about fog (fair enough given that magical fire seemingly doesn't work against it). Its range was 12", whereas in AD&D it's 1" per level.
Wizard Eye: Creates an invisible eye that can be controlled by the caster. It covers 3" per round, or 1" if you want it to examine the floor, ceiling and walls as it travels. It can see 10' in the dark (like infravision) or 60' in a lighted area. The material component is a bit of bat fur.
The OD&D version of the spell had a range limit of 24", whereas AD&D seems to have no limit except for that imposed by the spell's duration. The eye moved at 12" per turn, which is fast, and seems to make the 24" range even more ridiculously limiting. It had a duration of 6 turns, as opposed to 1 round per level in AD&D.