The Meta Liberation Army arc has changed the greater world of My Hero Academia, and the series has been putting a greater focus on the villains of the series as they have been challenged for dominance by a new villainous faction. Each of the villains have progressed in some way through this confrontation, and one that was particularly surprising was Himiko Toga, who through the fight had revealed a new ability gained for her transformation quirk.
The series sees her quirk completely power up and upgrade to the point where she can not only take on someone's appearance, but use their quirks as well. As pointed out by Whoeverthisis123 on Reddit, Horikoshi actually had teased this quirk evolution in a previous volume of the manga.
As noted by Whoeverthisis123, an extra page included in My Hero Academia's 18th volume revealed her original design before her official debut in the series. Along with the included details about her powers and initial design was a note that mentioned how she could use the quirk of those she transformed into. Toga's evolution in the Meta Liberation Army arc had some fans feeling like it came out of nowhere, but now it's clear Horikoshi had the idea long in advance.
In the arc, Toga uses the last bit of blood she had left over from Ochaco Uraraka. While she transformed as a way to escape from a group of attackers, her panic ended up unleashing Uraraka's quirk in the process. Showing off a violent new use for the gravity quirk, Toga realized that she could use the quirks of the blood she ingests. It was a pretty eye-opening for both Toga and fans of the series.
It's clear that Horikoshi has been setting the stage for many of the major developments for his series. Previous examples includes Shinso's hero journey, Shigaraki's origin story, and the fact that this is all supposed to be Midoriya's flashback. Now it's just a matter of keeping a much closer eye on the series for any potential seed that could bear fruit with major reveals in the future.
My Hero Academia was created by Kohei Horikoshi and has been running in Shueisha's Weekly Shonen Jump since July 2014. The story follows Izuku Midoriya, who lives in a world where everyone has powers, even though he was born without them. Dreaming to become a superhero anyway, he's eventually scouted by the world's best hero All Might and enrolls in a school for professional heroes. The series has been licensed by Viz Media for an English language release since 2015. My Hero Academia is gearing up for an even bigger end of 2019 with both a fourth season of the anime and second big anime film too.