I thought everybody knew the legend about what's-his-name composing it / receiving it as direct inspiration when he was on his way to be martyred. If you don't, I should look up the details for you.

Of course I did; that's the significance of it being inserted after ובכן לך תעלה קדושה, because that's when R. Amnon realised he was about to die. (As for everyone knowing it, aviva_m didn't, which surprised me. That's what you get for using a machzor with no commentary, I suppose. She's now a bit upset because ונתנה תוקף is tainted for her by this horrible story; it's the idea of her previously not having had the association that is strange for me.)

I thought I said, hatam_soferet's boyfriend margavriel taught it to me.

You said he taught you the piyut מלך אביון; I didn't realise he taught you all this extra stuff too.

If you didn't know, he's doing a PhD on the literature of piyyutim, so he really knows this stuff.

No, I didn't know that.