Togashi comes back and drops a huge bomb: Kurapika's unrevealed technique!!
Just like with Hisoka vs Chrollo last year, I wasn't expecting it this soon.
It may seem kinda OP at first but the conditions balance it out, especially the one-time use. If anything, it seems more similar to Leol's hatsu rather than Chrollo's. And it makes sense for a loner like him to have some variation and extra versatility whenever he works with other people. It may seem like a retcon but I don't think he could've used it in York Shin effectively if he had already developed it at the time... I don't think there was anyone whose ability would've come in handy given the requirements (Hisoka wouldn't have talked about his hatsu, much less if he wanted to fight Chrollo). Still, I think that, if Kurapika really wanted to fight on his own, his judgement chain should control people rather than threaten to kill them (that doesn't sound very honorable for a protagonist though, and of course, OP in the long run). He could've caught all the spiders with such an ability, even if he would use it just to interrogate them.
I wonder if he can only borrow the skill once per person (like a Geass) or as many times as he can inject them with the needle (provided they have aura)... It seems like the latter one.