I didn't get the vibe that Serwa's song would be mundane--that would be such a let down.
I'm thinking we see her in TUC still wearing that collar as a sign of how fucking badass she is.
+1 .
It certainly seems that it's the
gag, not the
collar that is the wrench in her (Kellhus') plan though, right? Or was that just how it seemed to me? So when the gag is gone, she can "sing" her sorcery again. Consider:
She did not sing simply because the watch she had sung for had come and gone.
Her next song would command fire and ruin.
Then he gags her. Next time we see her:
And it descended as lightning, the realization the she had failed.
Harapior had guessed her gambit.
I think she had sung, so that they would
not gag her, especially in the throne room. They would
want to hear her songs. The collar isn't important at all, I am sure there is a meta-Gnostic, or as I speculated elsewhere a Dunyain, way to defeat the effect of a collar. They collar her early on and yet, she only thinks about having failed when she is stopped from speaking.
Recall the collar only inflicts pain, it does not actually stop one from preforming sorcery right out. She is defeated by the gag. Once it's gone, the plan is back on, fire and ruin.