WARNING: The following contains spoilers for My Hero Academia Chapter #308, "Full Power!!” by Kohei Horikoshi, Caleb Cook and John Hunt, available now in English from Viz Media.
Chapter #308, “Full Power!!” of My Hero Academia puts the spotlight back on Deku, showcasing his newfound mastery of all the abilities passed down from the previous users of All For One. At first, it seemed like Deku’s demeanor had changed to a more serious one in the manga's newly begun arc, but this latest chapter confirms his main concern for the safety of others is still his priority.
The villain Muscular is excited to face off against Deku once again in Chapter #308, but the current wielder of One For All uses all the abilities to his disposal to make sure the battle damage is minimized. It’s still unclear how the usage of all these Quirks affects Deku’s body, which has long been his greatest hurdle in using the power-stacking Quirk on its own. A cautionary warning from the sixth user, En, hints at the future road bumps in Deku’s path, while also revealing that Deku’s absence was not spent entirely in solitude -- and it shows in how he handles the situation with Muscular.
Deku’s appreciation of each Quirk passed down via One For All is the underlying factor as to why the Quirks of the past wielders are effective in battle. En calls Deku out by telling him that he is treating them with too much respect. They should be used as handy tools, but knowing Deku, that is not a possibility. Deku’s admiration for Quirks is what lead him to acquire One For All. He truly understands what it means to be powerless, so to simply state that any Quirk is a mere ‘tool’ is an understatement in his eyes.
Although Deku appreciates all the powers that have been given to him, there is still much for him to learn about each Quirk’s threshold, and utilizing all the Quirks simultaneously puts a greater toll on his body. Being the ninth user of One For All means that Deku is currently feeling the most strain from the overwhelming power built up from user to user. En's presence indicates that he's still being trained by past wielders to better understand how to utilize their Quirks without burning out too quickly. And luckily for Deku, a more strategic approach to battling is encouraged by En, which is right up his alley when it comes to villainous encounters.
It also appears that Deku is trying to uncover the motivations behind each villain he encounters. After sensing Shigaraki’s true feelings, Deku can’t shake off the fact that even villains need to be saved. When it comes to Muscular, Deku discovers that his malice and lust for blood are not derived from any inherent suffering. But as Deku is also no longer afraid to make quick judgments in deciding when a fight is inevitable, he ultimately unleashes his full power against Muscular.
Since Deku is currently unaware of their movements, Shigaraki and All For One must currently be hiding in the shadows. Deku continues to collect information on them regardless, likely trying to figure out what their next move is. After all, Deku’s decision to leave U.A. High was All For One's pursuit of him. Currently, it seems like Deku has turned the tables on All For One and Shigaraki, which could mean that either Deku is currently stronger than both of them, or the two villains are not cooperating properly, which makes sense after All For One hijacked Shigaraki’s body for his own personal gain.
Overall, Chapter #308 does a great job in showing how Deku has grown as the ninth wielder of One For All. There is still a great amount of room for improvement, but Deku is back on his original path in terms of how to save others. He can only go Plus Ultra! from here.