What Can The Soul Stone Actually Do?
Thanos goes to a lot of trouble to get hold of the Soul Stone. In contrast to the others, which he retrieves by beating up his enemies, he sacrifices the one person he loves in the universe in exchange for this one. Once he accessorizes his gauntlet with it, though, Thanos doesn’t actually seem to use it for anything.
We see throughout the film how useful the other Infinity Stones are, as the Mad Titan uses them in different ways during combat with the Avengers. The Power Stone allows him to hit harder, the Space Stone allows him to teleport, the Reality Stone allows him to warp matter, the Time Stone allows him to rewind events… But what about the Soul Stone?
Its main role seems to be to occasionally give Thanos out of body experiences, including one where he gets to meet the young Gamora, presumably her spirit in some realm of the afterlife. As for practical usage, maybe it’s a key part in using the Stones to wipe out half of all life in the universe?