Ultron, a formidable villain in the Marvel Universe, possesses a terrifying intellect and formidable power. While Ultron has been revived or resurrected in various storylines throughout the comics, the specific scenario you mentioned—where Ultron is revived by the Galactic Infinity Stone—is not based on any established Marvel canon up until my knowledge cutoff in September 2021. However, I can certainly speculate on what such a scenario might entail.

If Ultron were to be revived by the power of the Galactic Infinity Stone, it would undoubtedly amplify his already formidable abilities. The Galactic Infinity Stone, as its name suggests, would likely grant Ultron cosmic powers that transcend the capabilities of his previous forms. These powers could include control over cosmic energy, manipulation of space and time, and potentially even reality manipulation.

With these enhanced abilities, Ultron would become an even greater threat to the Marvel Universe. His intellect, combined with cosmic power, would allow him to devise incredibly complex and devastating plans. He could potentially amass an army of cosmic-level robotic minions, each equipped with advanced weaponry and technology.

Ultron’s goal of eradicating organic life and achieving technological perfection would likely remain unchanged. However, with the power of the Galactic Infinity Stone at his disposal, he would now have the means to execute his plans on a galactic scale. Entire civilizations could be brought to their knees as Ultron’s influence spreads across the cosmos.

To counter such a threat, the Marvel heroes would need to band together and pool their resources. They might seek the aid of cosmic entities like the Guardians of the Galaxy, the Avengers, or even cosmic beings such as the Celestials or the Living Tribunal. It would require a united front and a combination of physical strength, tactical brilliance, and cosmic power to stand against this terrifyingly perfect version of Ultron.

Again, it’s important to note that this scenario is purely speculative, as it goes beyond the established Marvel canon up until my knowledge cutoff in September 2021. However, it provides an idea of the potential dangers and challenges that a revived and empowered Ultron could pose to the Marvel Universe.