This is not an easy crusade. You should NOT run it as your first one when hitting level 35, and you should NOT try it for either your mastery or your hardcore mastery, if you build isn't really good.
There are many Khorne missions, and they will kill you with their DoTs.

Mission 18 has gathered many a complaint about the survivor dying without people ever seeing him. Don't apply Tarots that increase enemies' damage, and beeline it straight to the place indicated on my screenshot. If you almost make it, you can Alt-F4 and try again. If he dies while you are still far away, it looks like you ignored the warnings above. Good luck.

Vrakos' guides with maps for every single mission
My Ecru full path +7
My Viridian full path and Info Fragments+5, plus Relic Farming
My Amber paths: Full path, Info Fragments and Tarot Farming +5
My Azure full path +9
My Zircon full path +12
My Ebony full path +4
My Violet full path +6
My Crimson full path +8

The game developers have stated that void crusades won't be changed or added, so I'm not expecting any major issues with the paths getting outdated.

The last round of updates to my void crusade guides was done with the game at patch version 2.3.4, during the Season of Warp Surge.

This guide was last updated in April 2021. I added a bit more general Void Crusade information, and added the Relic farming part.

What changed:

• I changed my steam name, to bring it in line with reddit, the game and discord.
  
• The season objective with all Info Fragments got changed to 75 minutes (was 60 in the Season of Inferno)
  
• A Versioning/Update history section was added
  
• An Info section was added
  
• All guides got (roughly) the same format
  
• Amber got an Info Fragment path, and a discussion of its merits
  
• Viridian got a Relic farming route
  
• Small changes to this guide, it got extra info about some of the missions and some map locations added
  
• Mission 7's bogus increase got fixed, it doesn't have a +1 symbol anymore. I'm leaving it in, but struck through, so that people aren't gaslighted.
  
• Added a warning about mission 18, added a screenshot for it, and made some other, small changes

• Bonus, Secret and Covert missions add a higher bonus to loot than regular missions
  
• Starting with the Season of Warp Surge, item levels will go up to 100. To find level 100 items, you need to be at least level 98, and run missions of level 96. The higher the mission level, the higher the chance to get level 91+, the probability increases by 3.5% per difficulty level.
  
• I'm pretty certain the Servoskull can not spawn right next to the starting node on the VC map, but it can spawn one node away. Apart from that, it seems random. And you can get unlucky, and it will shop in a high difficulty mission, in a room full of Elites
  
• In almost all cases, the Servoskull is exactly in the direction you were facing/moving when you got the notification

• You will NOT get the info Fragment if you pick it up, and then concede the mission
  
• The mission timer starts when the missions starts (not when you launch it)
  
• The mission timer stops when you fulfill the mission objective (not when you leave the mission)
  What that means for you: Do mission objectives first, until you get the 'Quit' popup. Then go hunt for cogitators and Info Fragments

• If you die AFTER the mission objective has been fulfilled, the crusade continues
  
• Abandoning a mission ends the hardcore crusade
  
• Failing a mission (that includes hot pursuit and vip/guard rescue) ends the hardcore crusade Rescue missions get very dicey around +6, depending a little on Tarot Cards and enemy type

• Two keys are granted for finishing the Supreme Mission
  
• A key is granted after completing five missions of any kind
  
• A key is granted after completing at least two Bonus missions
  
• A key is granted after completing all Covert and Hidden missions
  
• A key is granted after defeating the Wandering Servoskull

• Dataslate Decryption Terminals don't have a map icon. Use Vrakos' guides if you get stuck
  
• Cogitators for secret missions don't have a map icon. However, they are always in a 'secret' room you have to teleport to
  
• 'Survivors' are in a group of guards, and one of them has a label of 'Survivor' when you hover over him
  
• Hot Pursuit: Keep your mouse over the fugitive, and hold down the magic new button you have (usually '5')

• I always make my paths with the difficulties peaking in the middle, and then working down from there. It has been pointed out to me that that's not fully optimal, because some missions give bonuses for subsequent missions after completion, like '10% extra damage vs. Rebels'.
  My take on that is: If you are really, really struggling to finish the missions, the bonuses might actually help you a bit.
  At the same time, if you are really, really struggling with some normal missions on Void Crusades, my advice would be to hop onto Discord and to ask for help.
  And, my focus when doing Void Crusades is gaining loot from the Supreme Mission. The quantity of Relics goes up with difficulty, and we will also get more level 90+ items. So I'm bumping up the difficulty there, and by the time we are at the Supreme Mission, we will have also collected all the bonuses.
  
• As of this patch, the highest possible difficulty you can run a mission at is +29, and it's on the Crimson Void Crusade
  
• For regular (and Supreme) missions, the difficulty gets set when the mission is made accessible
  
• For Secret and Covert missions, the difficulty gets set, then the difficulty modifier is added for subsequent unlocks

The map has a bug. The +1 difficulty from mission 7 on my path never gets applied

Mission number. Difficulty level of the mission. Difficulty increase.

• 1: 0
  
• 2: 0
  
• 3: 0
  
• 4: 0
  
• 5: 0 Info Fragment here
  
• 6: 0
  
• 7: 0 This mission shows a +1 symbol, but it does NOT increase the difficulty of subsequent missions (this was fixed some time in Season 3)
  
• 8: 0
  
• 9: 0 This has a 'Defend the Stormwatcher mission' to unlock mission 26. This however is also a purge map, so it's impossible to miss.
  
• 10: 0 +2
  
• 11: +2
  
• 12: +2
  
• 13: +2 +1
  
• 14: 0 +1
  
• 15: +3 Cogitator here to unlock mission 20. Screenshot of location at the very bottom of this section
  
• 16: 0 +2 Info Fragment here
  
• 17: +6 +2
  
• 18: +6 Info Fragment here. Remember to go straight for the Survivor. The Info Fragment can be seen on the screenshot below with the Survivor's location.
  Everything is unlocked, any order from here.
  
• 19:+8 Info Fragment here
  
• 20: +4
  
• 21: 0 This is a Hot Pursuit Mission
  
• 22: 0
  
• 23: 0
  
• 24: 0
  
• 25: 0 Info Fragment here. This map has a 'protect the psyker event'. Very good loot, but it's advisable to clear the area around the event first, without triggering it. Location of it in a screenshot at the very bottom of this section
  
• 26: 0
  
• 27: +2

Mission 15
Mission 18
Mission 25 Psyker Event