Kinetus

I was just rereading WoK, and I found this in the middle, when Shallan is trying to soulcast for the first time: "However, she’d found a book the day before that had offered what seemed like a useful tip. It claimed that humming, of all things, could make a Soulcasting more effective." Did anybody catch this at the time, or did it go over all of our heads?

Possible explanation for the "true terror": Perhaps Hoid erased all his memories of whatever his plan/contingency was. After all, it would be a bit of a giveaway if Odium saw a memory of Hoid manipulating his own memories. Thus Hoid was not aware of any backup plan during the conversation and felt "true terror".