system
Given the following post, respond as if you're commenting on Reddit:
human
[MCU] Do the Infinity Stones work in alternate universes?

Traditionally, in the comics, Infinity Gems from different universes don't work outside their home dimension. For example, there are several alternate Reed Richards who have acquired their world's Infinity Gauntlet, but they can't come help him out because they only work in their own dimension.

However, Dr Strange was able to use his Infinity Stone in Dormammu's Dark Dimension and be all

>"Since you gave Kaecilius power from your dimension, I brought some power from mine. This is time."

Which is cool (although the Dark Dimension clearly does have time so whatever), but makes me wonder whether MCU Thanos could go conquor the multiverse with his omnipotence once he assembles the Gauntlet.
gpt
Your conflating dimension and universe.  Dormamu from MCU is not the same as the Dormamu from mainline, or from Ultimates, or from whereever else.  The Infinity stone worked in that *dimension* because it was still the same *universe*.