Acererak's Blackstone: (Wiz 9) Robert S. Mullin is a true hero of 2E era Greyhawk publication, creating many named spells and spellbooks with extensive Greyhawk lore. This spell by the infamous mage of the Tomb of Horrors is found in Dragon #225, Three Greyhawk Grimoires. It costs a dizzying 5000 gp and an Ioun stone to cast, but the Blackstone can absorb any magic cast at it or active effects that the stone encounters. It makes a good defense as well as a trap since it will explode if too much magic is drained. Good stuff!
Bigby's Silencing Hand: (Wiz 2) Bigby is a household name in D&D. His hand spells are superfluous in PHBs through the editions. However, for the true Bigby enthusiast, there is a TON of his spells (and all the Circle of Eight) in the sourcebook Greyhawk Adventures. They are in AD&D rules, but if you want 5E converted versions, go to Greyhawk Grognard and download his Wizards of the Flanaess. Silencing Hand is one of his lowest level spells that claps a magic hand over a foe's mouth. In a wizard battle this can be a game-changer!
Chain Madness: (Cl 6) I used chain madness once before in my 2E Iuz war campaigns. Very nasty spell. Starts with one target then exponentially spreads like a contagious disease to others. This spell is compliments of Iuz the Evil.
Drawmij's Light Step: (Wiz 1) For a 1st level spell this is genius. It's a limited levitate that allows a user to not leave tracks, walk on still water and even avoid traps that require pressure. Amazingly smart! Another Co8 spell from Greyhawk Adventures. See above for more info.
Evard's Black Tentacles: (Wiz 4) We all have heard of this spell. We all know how annoyingly effective it is. What I didn't know is Gygax debuted it in Dragon #67.
Fingerblade: (Wiz 2) This spell might not bear Mordenkainen's stamp, but in Dragon #242 he shared it in the article Jest the Wizards Three by Ed Greenwood. Mordy offered that this is a spell he used in his "younger days". This precursor to Mordy's Sword I bet, creates a force blade around the casters index finger. With it your wizard can literally sword fight with his finger. It can even break a non-magic blade by ending the spell. A quirky, fun spell for wizards who want to toy with low-level fighters.
Glassteel: (Wiz 8) Hey, D&D 3E through 5E, What ever happened to Glassteel? That's the entire entry.
Hextor's Fiery Eyes: (Cl 5) This is an improved version of the command spell. Rejoice DMs! Your evil clerics can now command a creature once a round, the effects last longer and it doesn't use a standard action. Shew! Find this spell in Dragon #356, Core Beliefs: Hextor by Sean K. Reynolds.
Iggwilv's Timeless Sleep: (Wiz 9) Another masterpiece of magic from Dragon #225. Our favorite Witch Queen wrote more than Demonomicon stuff. This high level spell from Iggwilv's Nethertome is an improved Temporal Stasis that can be programmed to end when the wizard's chosen conditions are met. Just what an evil archmage needs to keep some boss creatures on ice for emergency!
Jaran's Prismatic Blade: (Wiz 9) Robert S. Mullin is back this time with a rare spell from the Black One of the Vale. Imagine a force weapon combined with all the powers of a prismatic wall! Yes it is as deadly as it sounds. Check this spell out in Dragon #241, Greyhawk Grimoires II.
Kieran's Curse Ward: (Wiz 6) Want more from Mr. Mullin? Okay, here is an original spell from Kieran Jalucian, head of the Guild of Wizardry in Greyhawk City. The Curse Ward as its name implies prevents curses from affecting the caster, it removes existing ones, but it stops short of curses from artifacts or lycanthropy. Not bad! Locate more of Kieran's work in Greyhawk Grimoires. Dragon #268.
Leomund's Secret Chest: (Wiz 5) Len Lakofka's mage has many spells named for him, most using his extra-dimensional theme. Secret Chest has always been in the PHB and I like it because magically hiding treasure is a very D&D thing to do.
Meersalm Skin: (Cl 6) This little known spell from Dragon #354, Heironeous by Sean K. Reynolds, allows your caster to temporarily feel like the Archpaladin! It's basically an improved stoneskin spell that damages any weapon which strikes the protected creature. Love it!
Nystul's Blacklight Burst: (Wiz 4) Nystul is one of those Co8 mages I still know very little about. But sometimes you can learn more about a wizard through his spell selection. Blacklight Burst sounds, uh, dubious. Actually its a nasty negative energy spell that damages and slows targets. Locate this one in Greyhawk Adventures.
Otiluke's Siege Sphere: (Wiz 7) Another underrated spell from Greyhawk Adventures. Otiluke has alot of spells in this book, really any of them could work here, but I chose his highest level one because it gives me an idea what Otiluke is all about and that's evocation spells. He never struck me as a battle mage, but check out Siege Sphere. This boulder of force magic can take three forms, an exploding ball of liquid fire, an exploding ball of crystal shrapnel or an adamantine wrecking ball. No wonder Rary took him and Tenser out in Greyhawk Wars, Otiluke is geared for war!
Persuasive Oration: (Cl 1) A low level spell that is essentially just charm person for clerics. It is however perfect for clerics of Cuthbert. Find this useful spell in Dragon #358, Saint Cuthbert by Sean K. Reynolds.
Quicksand: (Cl 3) This spell is for clerics of Obad-hai. It's pretty self explanatory, you conjure a pool of quicksand in an area. You can find this spell and many more like it in the article The Power of Faith in Dragon #342 by John Ling, Jr. It's an interesting 3E era article I overlooked that requires you to take an "Initiate feat" to a particular god and it adds a few spells to your cleric/priest's lists.
Rary's Telepathic Bond: (Wiz 5) Of all the spells in GHA, this is one me and my players perhaps used the most. What isn't to like about a communication spell between a mage and two or more friends anywhere on the same plane? The upshot of this spell is that Wish can make the bond between any two creatures permanent. If a PC can achieve this life-long effect, then I hope their BFF must be quite high level as well!
Slerotin's Fortitude: (Wiz 9) Another top notch spell from Dragon #241. Who wouldn't want a spell created by the greatest Suel mage of all-time? This spell makes non-magical materials like a wall impervious to damage from physical and magical attacks. Yes, even disintegrate. Perfect for a Mage of Power who wants their tower to withstand a Rain of Colorless Fire perhaps?
Tharizdun's Maddening Scream: (Cl 8/Sor-Wiz 8) Yes this spell is as cringe-worthy as it sounds. It's similar to Tasha's Hideous Laughter, but much worse since there is no saving throw. My favorite part, the victim can only make reflex saves on a natural 20! I like to imagine Tharizdun cultists enjoy having this cast on them as a reward. You can find this nasty gem and others in Return to the Temple of Elemental Evil.
Vecna's Conflagration: (Wiz 5) One more from Mullin. Vecna's artifacts are quite renowned, but how well do you know his personal spell repertoire? Conflagration is like setting off a fireball centered on yourself, but the caster is unharmed and all your foes are knocked back. Sounds like a spell Vecna would employ all the time. Again, look for this in the pages of Dragon #225, Three Greyhawk Grimoires.
Wrath of Hextor: (Cl 4) This is another spell from The Power of Faith in Dragon #342. Your cleric of Hextor flips out against good enemies and deals an extra 2d4 damage with a flail. Just flails though. Could you imagine this spell used by six-armed Hextor himself? That's potentially 3-6 flails!
Xvarts must have spells right? Pass.
You know if anyone can find a good named-wizard or Greyhawk themed spell with Y in it, let me know in the comments. I'm wearing out here!
Zagig's Canned Laughter: (Wiz 1) Spell-master, Robert Mullin finishes off this A-Z with a humorous one from Dragon #270. Only first level, Zagig must've made this spell for his own amusement because all it does is creature disembodied laughter any time the caster says something funny. This spell would make for a crazy game night if combined with Tasha's Hideous Laughter and 5E's Vicious Mockery.