Gears of War: Judgment

You can obtain this achievements by playing solo.

Start a private survival on Terminal, at insane difficult.
Choose Sofia and play. Revive bots as soon as you can.
You could revive about 20/25 bots per game.

You can obtain it in about 1 hour without depending on others!!!

I would just like to point out that this achievement can be earned in Standard Survival. If you can't get enough players together or don't wanna join a boosting session, search for survival and if you don't get Terminal, back out and try again.

When you get in, the difficulty will be on Hardcore so there will be plenty of downs, especially on Scouts (Bots or Players) on perches as they usually don't notice Wretches climbing up and after 2 hits they'll go down.

If you get host and fail just restart from the beginning and keep going as the revives get saved. Should probably take less than 2 hours for most people.

Hope this helps, if you're going to leave a negative please leave a comment explaining why

Happy hunting folks

We found out the easiest way to get this achievement.

All you need to do is:

1. Gather 5 people
2. Find Terminal map in Quick Match
3. On 2nd wave kill everyone, except Rager

Now, it starts.

At first, choose the person who will get this Achievement. He stands few meters away.
All other guys should surround the Rager. He will kill everyone with melee. So, Medic should Revive all killed teammates. Try to Revive 2-3 at once. And do not let Rager to destroy the Hole/Generator. Also, you can beat him with melee. 2 punches is enough, so he will turn Red and now he kills with 1 punch.

So, that's all! It takes for about 10 minutes!

Sorry for my bad English.

I hope it Helps!
Good luck, Comrades!

*Little addition to Atom's guide*

I found it at least as quick as without, but sign in a 2nd controller and make sure you take the medic twice. This avoids bots taking the medic which will probably steal your revives then. Move your 2nd medic to a place where at least one bot of your team is. This raises the chance of one of those being shot down at one place. Ideally both of them so you can revive them with one grenade. When the locust approach the e-hole always move your 2nd controller close to it. As far as possible even in the centre of action. It's not that difficult to handle both controllers as you often only need to press a+forward to get back where you died before. Anyway you will be remarked with a red skull on your screen if there is someone you can revive so it will not distract you from reviving when you move forward with your 2nd controller. Got 50 revives in a very short amount of time that way.
If you vote negatively please tell me why so that I can edit my solution and improve others in the future.
Happy reviving!

Getting revives without boosting for it is balls. It's not explicitly impossible but mileage varies at best. The enemy Locust have a bad habit of making your teammates ineligible for revives by headshotting or gibbing them, and you almost always have to beat a friendly medic to the stim grenade toss whether you're trying to grind it out in normal matches or play Overrun solo with bots. I was getting a maximum of 5 revives per 15-20 minute match doing it solo, so I gave up fast and organized a boosting session.

The easiest method by far is to gather up 10 controllers to fill a private Overrun match. The host of the lobby is not allowed to have a guest controller in Judgment so you will need 6 people, 4 with a guest controller signed in. Put one person who needs the achievement on each team because both teams get a chance to defend as COG. Everyone on COG should be Sofia the medic and everyone on Locust should be a wretch. Bunch up the 4 COG controllers not working on their achievement and have as many wretches as possible meleeing them. Wretches cannot perma-kill the COG and can only DBNO them, so nobody has to go out of their way to be careful with who they're attacking. One small note about the roles of both sides, though: the wretch scream does nothing to help and Cole takes extra hits, so anybody with a screaming wretch or playing as Cole is slowing things down.

Using the above method, one person can complete all 100 revives in 6 minutes, or in other words, can complete their achievement before the round timer runs out. You can finish everyones' revives within 40 minutes. As an added bonus, letting the rounds end naturally instead of quitting to menu counts all of the wretch kills everyone is getting, so a good chunk of Professional Locust can be completed at the same time.