User blog comment:Lancer1289/All Good Things Must Come to an End/@comment-24174486-20130221183139/@comment-24174486-20130221200018

"All you know is that he created for that reason, not who created him or why he was created."

1. Do I need to know exactly who created the Catalyst in order to understand what it is and how it plays into the ending?

2. Read your own words (the part before the comma).

"It also properly foreshadows him, without Leviathan all you know about the Catalyst as that it's a thing you need for the Crucible."

The game tells you exactly what the Catalyst's role in activating the Crucible is, and in the end, it fulfills that role. And don't forget Vendetta, who tells you that the Reapers are the servants of the cycle rather than its creator, though it does not know who the creator is or exactly why they created the cycle. (Poor Vendetta. Its message was in vain...)

Leviathan doesn't foreshadow the ending; it flat-out spoils the ending. It would be just like if ME2 released a DLC where you learn that the Reapers' captured victims are processed into new Reapers.