This question came up in the Online 10-day Retreat Nov 3, 2020, guided by Delson Armstrong. Day 6 was part of a daily 30-minute discussion on the suttas, the Dhamma talk and reflections.
Slightly edited to improve readability
Formations are, as I always say, the carriers of Kamma. It’s the kammic impulses. It’s always the Formations that start to form the images and the feelings and so on.
But it’s the consciousness, which is hindered by ignorance and fettered by craving, which is to say that it takes that to be self. It takes the images that it sees to belong to a sense of self, and it craves for that being. So, because of that, that intention of craving drives forward that consciousness. I mentioned in the past that the faculty of intention is rooted in the Mentality-Materiality. It’s through that, that the process of the Formations arise and that gives way to the intention behind speaking, thinking and reflecting, and behind acting, breathing and so on.