Krethusa Omens of Doom
I'm fairly new to AoS and am having some trouble figuring out Krethusa's Omens of Doom. As I understand it, when you make a chanting roll you either cast the prayer if you roll high enough, or you bank the roll as ritual points if you don't roll high enough. But there is no choice. I can't roll 5 and decide "nah, I'll bank that instead" because a 5 is enough to cast Omens of Doom (4).
So how do you get to the 10+ possibility? With 10+ you can choose two effects, but you can never get there because in order to do so you need to roll 4+ ok the first attempt, which is enough to cast the prayer normally. And as far as I can tell Krethusa has nothing to add to her chanting rolls so I can't roll a 3 first chant and a 7 next chant, or something similar.
Am I misunderstanding something?
Edit: Figured it out. I was reading the prayer rules wrong. Don't know why it wasn't clicking for me.