Call of Duty: Black Ops 4

For this achievement you will need to head into the rush gamemode of zombies and gain a score multiplier of 100.

EDIT : Have been told that you need to pass 100 for the achievement to pop

When inside this gamemode whenever you kill a zombie you will increase your score multiplier by 1 (example if you were on a x5 you would move to x6). Other ways to increase your multiplier are things such as collecting yellow symbols that appear on the ground and picking up nukes. Your multiplier goes down when you are either hit by a zombie or do not perform an action that rises your multiplier within a certain time (about 25 secs).

Some tips for not getting hit by zombies are buying every gun/perk that you see so you always have ammo and sometimes perks may save you from being hit, also using the box and pack. these are both free and can be used every 30 seconds. GET THE SHIELD, THIS IS THE MOST IMPORTANT ITEM TO GETTING THIS ACHIEVEMENT. Another thing is that barriers can be rebuild instantly if you press , you can also constantly have traps on.

This took me a couple of matches to complete and you can also work on the other Rush achievements while going for this one. I did this on the map IX for anyone wondering.

Happy Achievement Hunting !

The other guides give a good overview of what to do but for a specific solution this worked first time for me:

Map: Classified Rush

Class: Aether Story

Perks (in order):

Stamin-up - really useful to keep from getting hit / getting to rush areas / collecting tokens
Death Perception: to see where zombies are coming from to avoid getting hit or swarmed
Victorious Tortoise: makes the shield really powerful and protects you (you can buy infinite shields in rush)
Timeslip (modifier) : charges Special Weapon quicker is the main reason to use this

Special Weapon: Ragnorok DG-5 - this is vital and the way you will build your multiplier/score and survive

Equipment : Wraith Fire (if unlocked otherwise your choice) - Wraith Fire is best since it last a long time, doesn't hurt you, and builds your special meter very quickly

Start Weapon: Doesn't matter much

Basically you're going to pick up a couple strong weapons from the mystery box or wall as quickly as you can, grab the shield in the second room immediately and cheese it while you are near it (keep buying it when it breaks). Whenever your special weapon is available use it to level it to 3. Buy perks right when they are available. Pack a punch whatever weapons you prefer.

Once you have all 4 perks you are going to use the shield and wraith fire or guns to build your special meter and immediately use Power Plant (Stage 3 Special ability) and by the time it runs out your special should be almost charged. Rinse and repeat and you should be able to kill zombies almost immediately and up your multiplier and score.

Multiplicitous 101 (15)
In Zombie Rush, get your score multiplier up to 100

For this achievement you will need to play the new zombies game mode RUSH. I recommend the classified map if you have it. Next start the match & try to keep your multiplier up. Timing is key. If you do not do something like get a kill or pick up a rush points every 25 or so seconds the multiplier will go down. If you take damage the multiplier will go down by half.

Here are some tips to not get hit: 1, grab the shield!!! 2, use the box & pack a punch. they are free & have a 30 second cool down. This may take you a few games to learn the map & the room order but it really is not a bad achievement. I created a video guide to show you how I did it on my first try. I hope you enjoy & if you have any questions just ask!!!