Yes, it is a good item, it gives a lot of stats. It's also expensive, and the bulk of CDR scares people away from it. I'd like to change that. Currently, it has these statistics:

Nashor's Tooth:
Recipe: Stinger (1090g) + Fiendish Codex(1125g) + 400g (2615g)
+65 AP + 50% Attack Speed + 10 Mana Regen per 5
UNIQUE Passive: +25% Cooldown Reduction

Ideally all that needs to happen is make it cheaper or give it an active, and change the recipe to remove some of the CDR. Removing Fiendish Codex from the build will help with this amazingly.

Proposal #1: Kage's Pick for easier acquisition:

Nashor's Tooth:
Recipe: Stinger (1090g) + Kage's Pick(765g) + 450g (2205g)
+65 AP + 50% Attack Speed
UNIQUE Passive: +15% Cooldown Reduction
This would accelerate getting to it, and leave the option of changing your build path, but it encourages getting gp10 items. Which feels cheap, honestly.

Proposal #2: Double Amp Tome for more AP:
Nashor's Tooth:
Recipe: Stinger (1090g) + Amplifying Tome(435g) + Amplifying Tome(435g) + 400g (2560g)
+75 AP + 50% Attack Speed
UNIQUE Passive: +15% Cooldown Reduction

More Ability Power makes it a stronger item for it's slot, and getting double Amplifying Tome opens up the option of going Revolver -> Gunblade instead, if you so incline.

Proposal #3: Give thee an active:
Recipe: Stinger (1090g) + Amplifying Tome(435g) + 900g (2625g)
+75 AP + 50% Attack Speed
UNIQUE Passive: +15% Cooldown Reduction
UNIQUE Active: Fire's Ancient Wrath at target champion, dealing 70+20 per level magic damage and increasing your magic damage dealt to them by 25% for 5 seconds.

Everyone loves Baron's debuff! Right? Right? D:

I'm open to any suggestions people are willing to make, this is simply my opinion on how to change it, if people feel it should be.

i like proposal 1 . gold per 10 items need more build paths and i like getting this item on someone like cho'gath but the buliding of the codex doesnt offer alot of power to someone like him its more the attack speed and cdr that im interested in . its similar to building wits end on him but helps him be more "magey" and use his spells more then once in a fight

Nashor's Tooth doesn't need a change. The item is good as is, the "problem" is the lack of champions who really benefit from attack speed and ap.

That was a problem before they made teemo's on hit .4 AP ratio.

This is the only problem I have with any of your suggested changes.

This, then Deathfire, then Blinding Shot, Lich bane autoattack, Absolutely NO way they will live. I think people would get it that don't even need it just for that buff, it's slightly op.

It is a great item, but it would be more applicable if it was treated similar to current AP items, and with the oncoming AP buffs to Kayle and Teemo, it'll need tweaking. You're right about AS/AP builds not synergizing too well with anyone, but bringing it in line with other AP items doesn't hurt either. Plus, that much CDR with all the new AP items and Ionian Boots is just redundant at this point.

Poppy's a far bigger abuse case than Teemo. Her Q converts all of her next auto attack into magic damage, last I recall. The funny thing is this was basically a direct port of the Baron ability, and I was far more scared of this on AoE comps when I considered it initially. Limiting it to your auto attacks in that period should be fine, I suppose. How do I write that to make sense?

Since the last patch it might actually be useful as in item. At least for teemo and kayle. It could also work for certain kennen builds, if it weren't for the mana. Diana may well use it, though I havent tried her yet.

To need a large amount of AP, AS, mana regen and CDR is such an uncommon combination, it suits very few characters indeed, still it may suit 2-3 champs now, rather than 0.