Warning! Spoilers for My Hero Academia chapter 311 ahead!
It might sound counterproductive for All For One to put a hit on Deku, and rightly so, since the My Hero Academia villain wants to extract One For All from the budding hero, and killing him would make that endeavor impossible. But by the end of chapter 311, it's made abundantly clear that All For One did in fact send an assassin after Deku.
However, based on said assassin's comments once she finds Deku comes back to All For One alive. If Deku comes back in numerous pieces, so be it. He just needs to be breathing. But then again, she could be bluffing. Unfortunately for Deku, the assassin currently has him in her crosshairs, leaving him with very few options. And the sniper rifle that's undoubtedly extending from the assassin's arm as a result of her Quirk is so massive that not even Delaware Smash nor Detroit Smash could save him.
Deku finds himself in this rather precarious predicament after making the decision not to attend U.A. High in order to protect his classmates and teachers from All For One, who has his sights set on him and his One For All Quirk. But there's also another reason for Deku going rogue. He's serving as bait to lure All For One out of hiding. And if All For One springs the trap, All Might along with the top three heroes (Endeavor, Hawks and Best Jeanist) will quickly descend on the scene, as they are currently keeping tabs on the young hero with a radio transceiver and GPS tracking.
But the assassin is quite a few steps ahead of the heroes and has just successfully disconnected Deku from his team. The moment before she makes her terrifyingly badass statement, she takes a shot from her Quirk-generated rifle, blasting Deku's radio transceiver straight out of his hand: "Follow my orders and I'll leave your limbs attached."
Obviously, the heroes' plan has failed on numerous levels, seeing as it was wholly contingent on Deku drawing All For One directly out of hiding. Part of their reasoning revolved around the fact that, earlier, Tomura Shigaraki had attempted to transform into his ultimate form, which, had he been successful, would have made him unstoppable. But because Shigaraki's transformation is interrupted, he is—while formable—not unstoppable. And now that Shigaraki is in hiding, it is assumed that he is utilizing this time to finish his transformation.
Since All For One is currently controlling Shigaraki's body, Japan's heroes knew that the best way to stop him was to somehow divert his attention, and what better way than to dangle the one thing that he wants more than anything else: One For All? But All For One obviously realizes that this would be their plan and comes up with a counter strategy that keeps him from having to venture out into the open. That's most likely why All For One hires the very assassin who currently has Deku in her crosshairs. But she's not alone. There's a figure leaning on a wall behind her, and it looks like Dabi. Although Dabi brings destruction wherever he goes, it's telling that he's there. Could it be that All For One doesn't trust the assassin or doesn't think she can pull the job off on her own? If that's the case, Deku could use this to his advantage. Throughout My Hero Academia, Deku has proven that he can quickly analyze a situation and come up with a strategy in moments even when under extreme stress. If there's a weakness, he'll exploit it.
