So I'm currently DMing DnD 3.5, using the Eberron system, because my gaming group wasn't up to trying out XD20 for our first campaign together.
Last session, my players learned what it is they're trying to recover from the ruins of Shadukar. With Eberron's origin legends being about it having been sung into existence, I decided that a music-related artifact would be an interesting wondrous item. So I decided on a set of Thaumic Tuning Forks. The idea is that instead of vibrating the physical air when struck, they affect the magical fields in the area.
After a small amount of research into metamagic feat rules and no small amount of debating with myself over how I was going to detail out this epic artifact, I think I've got the prototype of what it is and how it looks and behaves down.
There will be 5 tuning forks, each about 16" long, 6" to grip and 10" of fork. Each one has a unique symbol etched onto it, for which I used the Dancing Men font (because who doesn't want a Sherlock Holmes reference in their fantasy game?). Here's the image I slapped together in GIMP so the person(s) using the forks can indicate to me which forks they want to hit:


Note that I am NOT giving this artifact with an instruction manual. It's a puzzle for them to figure out. The basic way it works is, they have to strike at least 2 of the forks to get any kind of affect. Striking the right combination of 2 forks will cause the next spell within 10 feet of the user either randomly change the energy of a spell (acid/cold/elec/fire/sonic/subdual), increase the spell's range (touch spell given 30 ft range, all other spells get range doubled), double the spell's duration, or counter a spell as though dispel magic was used on the caster. Striking the correct combination of 3 forks (note: this requires either 2 people or a difficult DEX check) can give the next spell within 10 feet Empower Spell, Heighten Spell, or Widen Spell. Striking the right 4 forks together (again, 2 people advised) will either maximize the next spell or create a temporary Anti Magic Field.
Once (if?) the players figure out how to make an AMF with the forks, I will have an NPC that they're escorting to retrieve the forks create a "power pack" that's installable on the warforged character, which will be like a bolt-on backpack that can hold the 4 forks and keep them ringing constantly.
So, that's the idea as I'm holding it now. I have a chart in my GM notes saying exactly what combinations do what, so I can keep that consistent. Since this hasn't been acquired in-game yet, I'm open to any suggestions to improve this.
Note that there's spaces for more "correct" interactions, I'm not sure what to put in them, chiefly because I don't want them to be able to cast an array of spells with these… just affect spells that are being cast. I'm toying with the idea having one set of 3 that would make the spell ricochet randomly, and one set of 4 that would return the spell to sender, but I don't know if those effects would be too powerful. Also, because I LOVE leaving myself space for further expansion, I deliberately made it 5 forks instead of 8, so if I decide I want more possible effects down the road, it can be determined that there were other forks made that had gotten separated from the set.
Oh! I forgot to mention, the official name of this set is Linnell and Flansburgh's Thaumic Forks. Because if I'm going to make a musical epic artifact, it's gotta be named after the founders of my favorite band.