9. Titan Transformation - Shingeki no Kyojin
If you haven't watched or read anything about Attack on Titan then I suggest you skip this one out. Huge spoilers incoming! While this one isn't specifically an attack it does serve the purpose of boosting the users strength, stamina, and offensive capabilities massively. The name implies what it is. When desired the person is able to shed their human form and transform into a giant monstrosity. Once thought to be the scourge of human kind, the Titans appeared 100 years prior to the beginning of the story of Attack on Titan. Since then they began devouring humanity and pushing them to the brink of extinction. In the current age, with the Titans forever encroaching, humanity has been pushed back behind giant walls. While training to join the military force to push the Titans back, recruit Eren Jaeger discovers he has the ability to become the very thing humanity has fought against for over a century. While Eren loses all his ability to speak and think rationally, initially, he does gain immense size and strength. This enables him to begin to push the Titans themselves back. Gaining strength beyond belief, and carrying the hopes of humanity on his shoulders, Eren and his transformation have a well deserved spot on this list.