Hagan Lonovich wrote:
Right now I need an achilles heel. with him it may be easier because of his love to bask in destruction so perhaps he would unleash wormwood on earth or bring back the horsemen and watch.
Items like these are defined by their Achilles heel. Either they are "Seemingly all powerful but not nearly as useful as one would think", "All powerful with one unfortunate weakness to be exploited", or "not powerful in the way one would think." Don't think about it as "What ingredients make for an all powerful item", we all can think of a million Mega-damage, absolute invulnerability, etc.... Instead think of it in a "How do I use it in the story" way, and design the item around its purpose in the story. You're the GM, you don't have to follow any sort of item creation rules.
Storyline #1. I've always wanted to run this one. Where an NPC Rogue Scholar gets the item like this. He's not a *bad* guy (and the characters know this), but he's not the best, and he uses the item badly causing a lot of trouble, and needs to be stopped. He's not evil, it's just that the power is in the wrong hands. Luckily, he's not the smartest guy in the world either, so outwitting him is possible.
Storyline #2. I did play this one. The Item was All-powerful... at the time it was made.... but not right now. I ran a Supers game where a general obtained a 3000 year old scroll granting him an all-powerful army. And yes, the army was 5000 terra cotta warriors, and 3000 years ago it *Would* have been all powerful, but nowadays it's not as good (but still useful).
Storyline #3. The all powerful Item McGuffin. This one works well for Post-apocalyptic settings. A giant Scavanger hunt for an item of epic power! The CS is involved, the Fed of Magic, EVERYONE! And when the party actually finds it... the "Legends" turn out to be false... mostly due to the fact that they come from the notes from an ancient TV show about a "Gun that could destroy mountains". Everyone has been searching for a toy from an old TV show.
Storyline #4 (Another game module did this concept). The party hunts for All-Powerful item. Only to open the box and find it has been destroyed/decayed/fraud.. etc. Ok, no worries there... EXCEPT the other folks who wanted the item NOW think the party has it! And the party is hunted as a result.
Storyline #5. A bad guy gets the item, and now everything is bad with a capital B. It's everything the legends say.
Now you base it around some science fiction concept. Lets say it gives emotional control (A-La The Mule in the Foundation Series). Does this mean the party needs to somehow be immune to their emotions in order to fight him?
Lets say, instead, it gives near infinite physical power (matter control, telekinesis, force fields, etc), Does it have some other kink to it? Like the user has an addiction that can be taken advantage of?
Storyline #6. Bad guy has the item, and The Party is, for one reason or another, the ONLY group of people who are immune to it (the mind control doesn't work, or they have the only gun that can pierce the shield). Now it's up to them to save the world.
Focus on what the party is going to do concerning the item, then the abilities of the item define themselves. After all, in the end, this item, it's not a sword, shield, forge, robot, gun, computer, or hyper-magitech World Killing system..... it's merely a plot device.