I'm pretty surprised how you're underestimating the King in Yellow, JayTar. Normally,
you're the cautious one in the group. Pulling off a full set wide contamination in his own realm..
Without the sacrifice the saboteur play stands to get discovered in the first place.
We want to make the working undetectable to the King's denziens. That's the goal here. We need to pay something for that.. and we also still need the emotion with Elle to get things done till the finale, the first version sacrifices those things at the last moment instead of doing it from the get go.
I don't think we're getting undetectability for free, all magic working in the setting needs a price to be effective as we saw. So I added the essence bit as a clause.
The spark of soul was just poetic language,
@Blacksheep By life essence I meant a drop of blood - magical signature to spark the whole thing, like a detonation when we want to. Seeing it is designed to be inert.
Ideally, I'd feel more confident about this whole endeavor if we had the direct backing of the two Goddesses and the Dream God. Alas we're on our own.
Edit: Also, we are destroying the very memory. Not even trying to modify it into the spell, it's broken down to raw constituent - mana, and then we use it on the working. I keep stressing this because the Avatar of the Outer God in Peru
laughed when we used the Water of Forgiveness alone. We're in the King's Realm's threshold and this entity is a magnitude times stronger than the last one.