This is a strategy to completing the required achievements, rather than a list.
A few things to note about this achievement (and multiplayer in general):
This achievement will take at least 25 hours to complete. Each day will take 12-20 minutes, and each episode contains 2 days. You’ll have to fight 50 bosses, which means you’ll need play at least 100 days. There is a slightly quicker way, but I recommend waiting until you’re finishing up this achievement.
This game is currently glitched. Remember that when something weird happens or something goes wrong. There is a specific multiplayer glitch that prevents you from completing a mission and fighting a boss.
You can complete this by joining other people’s games. Sometimes this can be is quicker than starting your own game, and waiting for people to join you.
I recommend completing (but not 100%) the main story mode. You’ll know the game a bit and have better weapon blueprints available, as most of the weapon blueprints are found outside the mall area (you cannot find them in multiplayer).
Finally, use the vending machine for food and weapons. You’ll have plenty of scrap from completing missions to afford anything you need.
For the achievement, you need to complete the 4th level of certain PP trials.
These are the two PP trials you need to focus on for the achievement:
Speed Demon IV - Be the first to arrive at the Safehouse 50 times
This should be your main objective. The safehouse appears at 9:00PM. You’ll start to learn the safehouse locations for each day in each episode as you play.
Note: This CANNOT be done solo.
Like a Boss IV - Kill 50 bosses in Multiplayer
This should be your secondary objective. Bosses appear only after completing all missions in day 2. The first two episode bosses are easy; episode 3 and 4 bosses are difficult, even at a high character level. You can get to a safehouse only after beating the boss, if you’ve already summoned the boss.
I recommend completing the day’s missions and have the boss appear while going for the safehouse objective.
The three bosses at the end of Episode 4 only count as ONE boss kill. You can leave the game immediately after killing the boss and still get credit (good tip when soloing) - (Credit: Lt Warfarin)
The quitting tip is how you can kill more than two bosses per hour. My personal best is completing episode 1 in 17 minutes, so that only raises it to 3.6 per hour.
Note: One mission will have you destroy a barrier and then kill the Obscuris leader. Every once in a while, the leader is 17,000+ meters away! Still complete the day to be the first to the safehouse, but you will not be able to fight a boss.
Also – this can be done solo, but I would wait until you have completed all other PP trials that require multiplayer.
Focus on those two objectives to get this achievement.
You will end up with a lot of extra time waiting for 9 pm, as most of the missions aren’t difficult.
If you want to check the menu, go to the top level of a mall kiosk or behind a counter. Only fresh zombies can reach you, but if you kill a few of them, they won’t auto respawn and chase you.
Also – you will be kicked within 5 minutes of inactivity (no controller movement; browsing menus is fine) EVEN IF you are the host.
While you wait, you can also focus on completing the following.
All of these listed are also needed for the achievement:
Helping Hand IV - Revive another player 50 times
Try playing with people who are level 25 or lower. There are numerous skills that decrease the possibility of dying, so finding people who just recently started multiplayer is the only way to get this without boosting. (Boosting works if you can find a partner).
Note: There is a PP trial related to this: I Get Knocked Down – Finish a day where every player is revived once, but no one dies. I revived my random coop partner and then immediately got myself killed to he would revived me. I also kicked another player who joined late and still completed the trial.
Combat Medic IV - Heal allies for a total of 20,000 health
The character Connor (the hipster) starts with the Spray n Pray, although the gren-aid and rocket bandage work as well. Best time to heal players is in the safehouse. Everyone is in an enclosed space, rather than running around (and not getting healed).
All This Love to Give - Heal 3 different players in a single day
Same as above, but you need to be in a 4-player game. As of 12/31/16, it is easy to get connected to a 4-player game.
You can run around and heal each person if you’re having trouble, rather than waiting for the safehouse. The trial pops right away once completed.
Zombie Killer MVP IV - Earn the Zombie Killer MVP title (by killing the most zombies in a single day) 15 times
Not that difficult, but if you have a much higher score (and haven’t been reviving people), you should get this. 15 times will not be difficult while going for the other trials.
First Blood IV - Earn 15 First Blood bonuses
Get the first kill – use a firearm or explosive. 15 times will not be difficult while going for the other trials.
Team Building - Kill 500 zombies in a day as a team
You’ll get this while playing with 3 or 4 people without even trying. Once again, not difficult if going for the other trials above.
After you get this, it will continually pop up as a glitch. Don’t worry; the trial will stay completed.
After you have completed the Speed Demon and Like a Boss trials, you will have also completed the following:
Epic Loot IV - Kill 50 loot zombies
Day Tripper IV - Complete 50 days in Multiplayer
The final PP trial you might have left is:
Teamwork IV - Complete 250 missions in Multiplayer
These are the starting missions and not the kill XXX zombie missions.
After defeating 50 bosses, you’ll have over 150, as you need to complete the day 2 missions to fight the boss.
Episodes 3 and 4 have more missions, but they are harder and more time consuming, especially solo.
Hope this helps as way to tackle this time consuming achievement.
Any thoughts or comments, let me know.
Finally, here are the additional PP trials that can be completed while trying to complete the above.
Note the Geronimo achievement – it will be difficult to get if you have too much health or bought too many skills:
Bling I, II, III – Create 1/5/10 Gold Combo Weapons.
Holiday Hellraiser – Complete 3 missions in episode 1.
Plaza of Pain – Complete 8 missions in Episode 2.
Boardwalk Butcher – Complete 12 missions in Episode 3.
Amazonian – Complete 15 missions in Episode 4.
Looter I, II, III, IV – Loot 5,000/20,000/50,000/100,000 scrap from zombies.
Glutton I, II, III – Eat 10/20/30 times in one day.
Counting Calories – Survive a day without anyone dying or eating food.
Pacifist – Survive a day and complete a mission without anyone killing a zombie.
I Get Knocked Down – Finish a day where every player is revived once, but no one dies.
Close Call – Reach the Safehouse with less than 50 health.
Geronimo – Lose more than half your health from falling damage without dying.