Code:
> sing c
You continue to dance.
[HP:100%] [ME: 98%] [PE: 97%]
>
You dodge Elder Aijina's attack.
You dodge Elder Aijina's attack.
Your flaming bite burns Elder Aijina's head.
Your flaming bite lightly burns Elder Aijina's chest.
Your flaming bite burns Elder Aijina's chest.
Your flaming bite starts Elder Aijina's chest on fire.
Overall, Elder Aijina has quite a few wounds.
[HP:100%] [ME: 98%] [PE: 97%]
> A strange compulsion keeps you from attacking Elder Aijina.
You chord rings through the air unheard.
I was engaged in melee, it wasn't a reaching weapon, I was solo didn't even have a pet, and I have C major mastered. It still does fail occasionally, but it only worked one out of five times in that fight. The other four were apparently stopped by sanctuary.
Edit:Tested it again and it only seems to happen if I'm dancing while singing the chord.