Misaka may be on her last legs thanks to ITEM's efforts, but with the rest of their crew dispersing and leaving just Mugino to deal with the intruder they've been paid to handle things are at least looking a little more even-handed for our protagonist.
If anything, this battle of the Level 5s sees its balance tipped in Misaka's favour thanks to another blunder by Frenda, who has left a slew of her doll-shaped bombs laying around the complex just begging to be used. Thus, it's these props which take centre stage in the face-off between the Railgun and Meltdowner, with Mikoto refusing to give up on her plan of destroying this facility as she attempts to outrun, outgun and outsmart her opponent.
Having succeeded in outsmarting Mugino, Misaka reaches her goal and destroys the core of the facility in question, only to find that her victory against her opponent was an overly short one. Thus, it's now time for an exhausted Misaka to try and make her escape against a now-furious Mugino - something that she succeeds in doing, but not before piquing her opponent's interest in exactly why she's so dedicated to her task. With only one facility left to go, Misaka is on the brink of achieving her goal, and finding that facility empty and disused suggests that the job has been done and she can now get on with her life.
As per the past couple of episodes, this was another demonstration of A Certain Scientific Railgun providing its action-packed best, making good use of its two main players in this scenario and their respective powers to provide a fascinating and visually engaging match-up that, coupled with the personalities of the characters themselves, was simply great to watch. Of course, this arc is far from over yet, and the appearance of a certainly Kamijou Touma is only the pre-cursor to further developments here...