The Marvel Cinematic Universe has had a decade to introduce its six most powerful artifacts, the Infinity Stones. In that time, though, only five stones have materialized. The sixth, the Soul Stone, has yet to be introduced, with many fans assuming that the all-powerful gem will make its debut in the upcoming Avengers: Infinity War.
There may be a good reason why the Soul Stone is currently missing in action. A recent movie tie-in comic, Avengers: Infinity War Prelude, described the Soul Stone as the most dangerous of the Stones, and the one the universe would least like to see in Thanos’ possession. Considering that the other five stones grant their wielder mastery over space, reality, power, time and mind, it is worth pondering what makes the Soul Stone so special -- and so powerful.
To fully explore what the Soul Stone is capable of, and what makes it so dangerous, we need to look to its comic book counterpart, which was originally called the Soul Gem. First introduced in Marvel Premiere #1 back in 1972, the Soul Gem started off as a gift, handed down from the High Evolutionary, a scientist-turned-cosmic being with the power to evolve and devolve things at will, to Adam Warlock. Using the Soul Gem, Adam Warlock helped save the planet of Counter-Earth.
Things got strange for Adam Warlock after he departed Counter-Earth, learning in short order that the Soul Gem was sentient, and that it had an innate desire to consume souls. But that is not all. Once a soul was consumed, it resided within a reality created and contained exclusively within the gem. The gem’s wielder could then access the skills and memories of those imprisoned. The gem also has the power to effectively read minds, allowing the wielder to peer into the soul of another and glean information.
That might not sound as sexy as being able to punch Captain America back to his enlistment date (literally) or the freedom to teleport vast distances at will, but the Soul Gem comes with its own offensive abilities. Those include the power to attack an enemy’s soul or revert them back to their natural state (Adam Warlock did this on Counter-Earth when he reverted the New Men, animals evolved rapidly to create a race of man-beasts, back to their original, unevolved forms).
That might not sound like much, but consider the Soul Stone’s power for a hot minute. The MCU’s heroes use all sorts of energies and projectiles to lob attacks at enemies, but the jury is out on whether audiences have seen soul-based magic. The only person likely to know what such an attack would look like, let alone how to defend against it, would be Doctor Strange. As for reverting creatures back to their natural states, well, what is the Hulk if the Soul Stone prevents Bruce Banner from maintaining his transformation? All that reasoning could be null and void, though, if the Soul Stone can simply trap someone inside itself, effectively erasing them from a fight.