What you need is an Artifact of Power. Each is an item, tool or device capable of astonishing feats, typically (though not always) independently from any supernatural abilities of their wielder (though they don't necessarily need one), that outstrip anything else that their world can offer. Unlike some types of phlebotinum, Artifacts of Power are not naturally occurring: they are constructed. (The word "artifact" literally means "something made by humans," and contains the same root as "artificial.") They can range from the simplest Magic Staff to the most complex construct and don't even have to be magical either, though what else can anything on that power level be?
To be precise, the thing that separates Artifacts of Power from regular tools is rarity. Modern explosives might do a far better job than a Wand of Fireballs in causing explosion-based havoc; explosives, however, are (relatively) easy to manufacture today, whereas fireball-shooting wands in many settings won't be. If they are, then, though powerful, they in turn aren't artifacts; the Legendary Wand of Angkor Wat, on the other hand, will be one. As a result, Artifacts of Power are frequently either one-of-a-kind, the methods of crafting it lost to the mists of time; made of a substance that is difficult to find; or incredibly, incredibly hard to produce. This rarity, in combination with its might and utility, will often make an Artifact of Power an object of desire for a great many individuals and organisations, both savoury and unsavoury, meaning that a MacGuffin has a good chance of being one.
Common categories, not mutually exclusive:
- Amplifier Artifact: Objects that enhance preexisting abilities.
- Ancient Artifact: Objects that are old and powerful.
- Anomalous Art: Works of Art with supernatural properties.
- Animating Artifact: Objects that provide life to the lifeless.
- Artifact Domination: Objects that controls the wielder.
- Artifact of Attraction: Objects that forces people to want it.
- Artifact of Death: Objects that kill its wielder.
- Artifact of Doom: Objects that are Made of Evil.
- Counterpart Artifacts: Artifacts that complete a set together.
- Famously Mundane, Fictionally Magical: Real Life objects with fictional origins.
- Immortality Inducer: Objects that make its user immortal.
- Instant Allegiance Artifact: Objects that give power, but can also corrupt the user.
- Protective Charm: Objects that protects the user.
- Public Domain Artifact: The same objects used all across fiction.
- Summoning Artifact: Objects that can summon entities.
- Upgrade Artifact: Objects that make the user an Instant Expert.
- Artifact Collection Agency: Organizations tasked with collecting Ancient Artifacts.
- Imported Alien Phlebotinum: Objects made by or given from aliens.
- Set Bonus: A set of objects that work better together than apart.