Possibly the most powerful superhuman ability is Power Mimicry, which is the ability to copy and use the powers of other superhumans. In various forms of fiction, there have been different depictions of this ability such as with Amazo from DC Comics, Sharingan users from Naruto, and Peter Petrelli from Heroes. Sometimes users can only use one copied power at a time, others can use multiple copied powers at the same time, while a rare few can use every single power they copied simultaneously to completely overwhelm their enemies. That is why Power Mimicry could be the strongest superhuman ability because there are thousands of known powers and this ability could potentially give the user access to all of them, which would be the closest to godhood a superhuman could possibly reach. I am think of giving this power to the main character of my sequel trilogy and it will not be unmatchably powerful at the beginning, but he will gradually learn to control his growing ability to reach the highest level. It will have considerable psychological effects on the character as he tries to digest each power he copies, which will be similar to the way I struggled with my autism.