In Infinity War, Dr Strange transmuted a black hole created by Thanos into butterflies, using a spell.

Something that should be said about black holes is that they aren't just a region with strong gravity. It is quite literally a region of space where the warping of space is such that the location of a particle existing as a function of time reaches its end point in the singularity.

Usually this is achieved by grouping together mass in such a small point in space that the gravity achieves this. However, in this scene, it seems Thanos is not creating the singularity by making mass, but rather he is bending space itself to achieve this bending of space-time.

This is supported by the fact that he uses the Space Stone throughout launching the singularity at Dr Strange, and by the fact that there's an energy field around it, seemingly containing its power. What this all means is that the black hole is actively being formed throughout the duration of the attack. This is significant because Dr Strange, with his magic, seems to be able to quite literally compete against the Infinity Stones' hold on space itself, at least in this attack, to the point where he can warp space to undo the attack.

This is also impressive scaling for Thanos as well, because it establishes that Dr Strange has the ability to do what no amount of energy can, which is overcoming a singularity. At the same time, Dr Strange is stated several times by himself and the directors to have insufficient capabilities of killing Thanos.

According to traditional scaling, this would very strongly imply that Thanos should be pretty much unkillable or indestructible by any conventional means (also stated by the directors, meaning this isn't out of the blue). Also, it is pretty impressive that Dr Strange not only transmutes a black hole, but also does it against the will of Thanos using the Infinity Stones.