The highest possible discount (dropdown offer) is only available after having watched the masterclass. It is first offered at the end of the masterclass, on the same page where you watch the masterclass (please don't close the browser window before the end, to avoid losing the immediate offer). A pop-up window will give you an opportunity to enrol right away at the lowest price.
After you've decided not to enrol at the highest possible discount, the dropdown offer won't be available any longer, and the fee will be increased. Following that, yet another discount becomes available. It's called a special offer/rate/discount. This discount is also available for a limited time only (for a week) after having watched the masterclass. After one week, you can purchase the quest for a full/regular price.