Where can I find a Complete Spoiler list of Risk Legacy's packets & pockets?
A complete list of what is in each packet can be found in this PDF I have made publicly available. 

I wasn't able to find any one distinct source, however by reconstructing the starting powers with the help of this question Which Faction Power will result in the greatest bonus troops and/or fewest troop losses? and reading a series of blogposts giving a breakdown of a campaign on BoardgameGeek I was able to come up with a comprehensive list to help me and my friends play a new campaign with our existing map.