Aliens vs. Predator

Go to Single Player/ Then Single Player Survivor/Chose Mausoleum.

When you start kill every alien except for one, alien count in the top left corner. Let it take down one-third of your health bar, then run away and hold Y to heal, keep doing this until the achievment pops. If you run out of stims you can pick more up, they also respawn.

I BELIEVE this needs to be done in a single match but I'm not sure if anyone finds out please leave it in the comments.

The quickest way I found to do this was on the level Mausoleum of Survivor Mode. What you need to do is keep running around the map in circles, grabbing stims, and then grabbing grenade ammo.

Once you have this, just shoot the wall in front of you. Just make sure your not to close or instead of bring you down 2 health bars it will kill you. Then use a stim and wait for the grenade ammo to respawn.

If your playing singleplayer, Ive noticed the grenade ammo takes forever to respawn. So you should probably start letting the aliens take a swing at your health. Then of course use the stims.

Good luck!

Load up Mausoleum

Note
All 30 blocks need to be regenerated in the same game

Start out killing all the aliens except 1.This level is alot easier to control than the other map. All you need to do is let the alien hit you a couple of times,run away and heal. Keep going untill the achievement unlocks. The Stimpacks respawn around the outside walls.

If you are going to vote negatively please leave a comment as to why so i can make my solutions better

I found the easiest place to do this was the cell block level; its better lit than the mausoleum.

The trick is to stay in the long corridor and not go through the door when it opens unless you needs stims or ammo. Just run from one end to the other, turn, and lay waste w/ the shotgun and pulse rifle. Then run to the other end and start over. Just keep using the stims that will regenerate outside. The trick is just dodging the aliens which isn't too hard if you utilize the melee attack.

Very easily done on the Hive map with four friends. Personally we split up two on one side of the map and two on the other. Then I just ran around the railings with a shotgun until about wave four and received the achievement. Just make sure to heal yourself very often. And yes this needs to be done in a single match.

Note: In order to get this achievement, you just regenerate all 30 Blocks of health within 1 single game. We tried this in multiple game modes and it didn't count at all!

I would like to give credit to CauldronOfDeath and Domanator316 for helping me discover this method.

There is an easier way in which you can get this achievement rather than relying too much on the Aliens. In order to do it though you will need at least 2 - 3 players to help you work on it. You can have 4 but you will have more Aliens to deal with at the start.

First you will need to get whoever is the host to set up a Private Player Match in Survivor on the Mausoleum Map. Now on this occasion Friendly Fire must be turned "On". They then need to invite the amount of people that are playing Survivor and then once everyone's in position and ready to play, the host can then start up the match.

This Survival Arena is based in a dark temple with a square platform lit by the sunlight and pillars around it. The Aliens will lurk around these dark areas so I recommend you stay in the middle. Ammo will be around the back areas as well, but importantly there will be approx 4 Stim Packs which are labeled with Green Health Packs and those are the items you need to run along and grab more than anything.

Now as soon as the game begins, you will all need to work together and take out the Aliens but keep 1 of them alive...

Player Differences With Aliens For Waves...

1 Player: Wave 1: 6 Aliens - Kill 5 Of Them
2 Players: Wave 1: 12 Aliens - Kill 11 Of Them
3 Players: Wave 1: 18 Aliens - Kill 17 Of Them
4 Players: Wave 1: 24 Aliens - Kill 23 Of Them

Now when you have the last remaining Alien you will need at least 1 player who has some running skill to train that Alien and make them follow it around at all times. This is done by using the to sprint regularly and blocking by pressing & at the same time. Use Stim Packs () if you need to, but don't let your health bar go just down to 1 or the Alien can execute you. Don't shoot or melee the Alien or you could kill it.

This is the reason why you need at least 3 people in order for this method to work. Whilst the lonesome player distracts the Alien, the other two can work together to get this achievement. For this get the two of you to stay around the middle of the lit arena and then whoever wants the achievement needs the other person to pull out their Pistol and shoot them (Friendly Fire). You need to be shot 3 times which should reduce your health by 1/2. Then you hold down the button and use a Stim Pack. You can carry up to 3 but I recommend keeping a spare in-case the Alien changes directions and attacks you. When your out of Stims sprint to a Health Pack and then return to the lit area. Rinse and repeat until that person gets the achievement. It will pop during game-play. You can then do all of the same for the other people that need the achievement as well.

Now it is possible that the Alien will get bored and will decide to go for the other two players that are doing the Friendly Fire method towards the achievement. If this is the case the Alien will focus on one of you only so you will need to lure the Alien to the player who was originally training them around. If the Alien attacks you too much, remember to block using & to avoid death. Once you believe the Alien has got it's attention to the trainer, quickly sprint back to your partner and continue to do the boosting.

This achievement overall is do-able using this method and it's way easier to progress than relying on the Aliens attack, but you all must do teamwork and communication in order to make this successful.

Good Luck!