Copy from the Compendium:
Hidden and Covert Missions can be unlocked by completing hidden events or finding secret info-fragments. These missions give further unique loot bonuses or allow more tries for the player
Supreme Missions are located at the end with challenging bosses and missions
Completing objectives and missions on the Void Crusade map rewards players with Keys
Players may acquire a total of 5 keys from the Void Crusade
After finishing a Supreme Mission, players can use a teleporter on the map to get transported to the final loot room where they can open Void Chests
Players may open as many Loot Caches as they can with the number of acquired Keys at hand, besides the Supreme Void Chest which does not require a key to open
There are many ways to do a Void Crusade, but personally i choose the easy way, as I dont see the point in doing only 1% damage in missions.
1. Do all 3 missions which are unlocked at the start.
2. Do all right side missions.
3. Then do all left side missions, and last go for the middle.
4. Do Covert / Hidden missions as soon as they come up.
5. Depending on your skill, do the nurgle supreme mission (right) for easy gaming, 4 levels high, 25% less damage. If you are geared up do the left side, 90% damage reduction, as there is much more loot and mini bosses. Its not to uncommon that they drop mem-viruses.
I do not garantee it, but I am pretty sure, that the chests are always the same. So if you know where the morality chests it, i am positive that it will be the same chests in all void crusade runs.
Nevertheless, I can not find the last info-fragement, and would be pleased it anyone knows where to find it. I marked on the map below all locations i am aware of.
Please ask me if you would like to know more, either here, or in-game, Anthrax Omega.
Good hunting, battle brothers.
Edit: Chest locations seem to be determined by how many missions you did on the void crusade. As i do always all missions, it seemed for me, that the location for the chests are fixed.