Now I don't take credit at all, not in the very LEAST for this challenge guide, but a link is below to a great guide i found while raging on the "Second Chance" challenge for killing 5 enemies with car explosion. It is a work in progress, but I will copy and paste the hardest ones, or at least the ones I had the most trouble with, for each mission, remember NONE if this is mine, all credit to NakedAssassin at Xbox360achievements.orgMain story missions:Mission 1 Pyrrhic Victory:Dive to prone on an enemy grenade and survive- There is a flak jacket on the ship, in a crate just by the right hand MG. Then at the very end of the mission, when your friends are waiting for you by the beach. Hide behind the tree that is directly to the right of them (Don't go so far towards them or you'll end the level). Use your weapon to clear out a few enemies as even on recruit they will kill you quickly. Then just hang around and wait for a grenade to be thrown at you, try to spot it coming in so you can move away, then sprint at it and hold down the crouch button (Default B) to dive onto it. On recruit and using the flak jacket, this should be easy. Just be patient. A note as well, you must be at full health to not die, hence clearing a few enemies from the area is advisable.Mission 2 Celerium:Eliminate 4 enemies with one round from Titus weapon- Note that the Titus has 2 fire modes, buckshot and explosive, use explosive. Try this throughout the mission. Possible the easiest place is just after you rescue Erik in the container, when the attack comes. (I [the TA User] found that the best place is to get to the elavator inside the base before all your allies, then as son as the doors open, fire the explosive rounds, it should impale and kill one or two guys then kill the others for the challenge)Mission 3 Old Wounds:Eliminate 15 enemies with pulwar sword- After the opening scene and BEFORE you get onto the horse, look to the back left of the area and there is the sword sticking out of a skeleton. Use this throughout the mission to get 15 kills.Destroy enemy helo with a mortar- After the meeting in the cave, the mortars are to your left by the exit. Get back on your horse and ride to the exit, after your horse rears there is a helicopter that comes low to drop off some troops. Spam your mortars at it to destroy it.Destroy 4 enemy helos at North Pass- After blowing the arch, you will jump back on your horse. Head to the left and you will see some tanks rolling over the hill. Go over this hill and you will see 4 helicopters, wait a few seconds and they will be targetable by your stinger. Take them all out.Mission 5 Fallen Angel:Burn 10 enemies with flamethrower attachment- When you get spotted by Menendez, you will take control of a CLAW. Use the left trigger to incinerate 10 enemies. Also at the start of the mission, you can run up to a CLAW on the left and access it to enable the flame-thrower, not sure if this is needed or if once activated, any flamer kills from it count, but doesn't hurt to turn it on here.Protect 2 CLAWs from destruction- When using the CLAWS to aid your escape, make sure to kill as many enemies as possible and switch to the next one in good time. When you're controlling the 2nd CLAW, shoot the drone helo's down first, then there are a few RPG troops that come in on the rooftops and ground. You can also switch back to the 1st if you need to.Deploy SOC-T boost to find 2 alternate routes- When you're driving the car at the end of the mission, do not follow the other vehicle, instead go to the other side of it. There are a few areas here, for instance one where you will jump over the highway, use your boost before jumping and whilst passing these areas.Mission 6 Karma: (This one is easily the most annoying because of the long *** walking scene you can't skip at the beginning, combine that with the ziggy challenge and you got yourself an anger stew)Obtain retina scan in less than 60secs- When you use the little robot 'Ziggy' at the start, race through to the objective to get the scan, use jump to get extra speed (Don't jump in the small pipe), may take a few attempts as timing is tight. There is a mission clock in the lower left which you can use to gauge your time. Apparently Ziggy can sprint however I've not noticed a speed difference. There is also a checkpoint as you enter the pipe room, if you get to the grate at the end that you must shoot to open, and the clock is past 52 seconds, you're probably best to go back and check out Ziggy's flying mode in the pipe room instead of opening the grate. It will take a few attempts so it has been mentioned that as soon as you control Ziggy, if you sign out of XBL then back in, you will save that checkpoint, then if you're failing, sign out/in to reload that checkpoint. (here is a tip I found on YouTube "GUYS: 4 ways to increase your ziggy times:1. look in the video and jump when this guy jumps its faster than walking2. hold down L3 to increase speed it does work3. in the pipe room just before you finish strafe jump onto the pipes4. when youre running down to the? grate at the end instead of walking to it and zapping it jump and let gravity drop you down to the grate then zap it and kill the guy u fall onto"The YouTube video link isEliminate 5 rappelling enemies- There are a couple of enemies rappelling in the mall towards the end, and a few more outside coming down from a helicopter.Eliminate 25 enemies in the outdoor area- When you start chasing Defalco, there are plenty of enemies to kill throughout this area. Make sure you kill every one you see.Mission 7 Suffer With Me:Perform a knife throw at enemy guard post- This is done at the very start as you climb the ladders.Survive an enemy RPG blast which causes enemy collateral damage- You need to be shot at by an RPG and have it kill a nearby enemy. The first place you can do this is by Noriega's jet, if you throw down some Nightingale's and try dancing with a few enemies, you may get lucky and be shot at by an RPG. Otherwise keep your eye out during the level for RPG enemies, and stand near others when you see them.Distract 8 enemies at the same time with Nightingale grenades- You get the Nightingale grenades just before you enter the airfield, there in a crate near where you see a propeller plane. A note is that you can throw several in different areas, you don't have to use just one. Can be done as soon as you head down and outside, by Noriega's jet, throw a few down. Easiest done as you're escorting Noriega though the area, you will come to a park area, throw one in there and you should get it. Otherwise keep using them when you see a group of enemies and restock ammo before you run out of them.Destroy Noriega's private jet- On the airfield as you head outside, there is a Jet on the runway and you're told to destroy it. Shoot it with grenades or any explosive you have.Destroy 1 enemy ZPU- Located in the outside area, after Noriega's receives a pistol. Keep your eye out for it. It's an Anti-Air gun located on top of one of the buildings. Should get it when spamming the IR strobe. Will update with a better location description.100% survivability rating- At the end of the mission a IR strobe gets thrown in and a gunship arrives. This can be very frustrating, if you move too fast you will be shot, too slow and the same will happen. Try stay just behind Noriega, and make sure you don't jump too soon or you will simply fall to your death.Mission 9 Odysseus:Direct CLAW to eliminate 25 enemies- At the very end of the level, you go up on one of the plane lifts. At the top to your left there is an access room, use this to get the CLAW, then use it to kill 25 enemies as your make your escape.Mission 10 Cordis Die:100% impact ratio with SAM engagement on highway- At the very start you will have to use the SAM. Wait for the missiles to say 'Lock' and for a clean shot before shooting. This one can be a pain and seems reliant on luck, they tend to always come behind you, so keep scanning the skies and wait a few seconds for the lock, then shoot. There are a couple of obstacles you should be wary of before shooting rockets. May take a few attempts so be patient.Rescue trapped SSA in damage vehicle- When you encounter the 2nd CLAW, ahead of it to the right there is an access area you must use to rescue the SSA.Protect G20 cougar at intersection- After the mall area, you will head outside and down some stairs. Ahead of you is the truck you need to protect. Behind it and on the roof are enemies with RPG's, try to take them as soon as possible.Destroy 3 drones with one shot- Appears when flying the Jet, and you split from the convoy to take out drones, you can destroy more than 1 with a missile, if you hit one in a cluster. Try using the skyburst missiles (LB), and you should unlock it. dieredsparowes has pointed out that you will need to replay the mission on the difficulty you originally completed it on in order to use the skyburst missiles, however goregutts has said that if you rewind the story, then complete it on recruit, the next time you play it, they should be available. A little confusing but if you're having problems, see if that is relevant to you.Mission 11 Judgement Day:Destroy ALL laser turrets- These are scattered around the starting area. There are 2 up high to the left on a building, another 2 to the far right. Then a few scattered around at the very back and one just up in front of you. They look like normal search lights, and a few shots from a sniper will destroy them. Get up high on one of the buildings and keep searching till you see "Career Record Updated" appear.Eliminate 5 enemies with one strike of the kinetic projectile weapon- From the start of the mission, head up the stairs and keep going straight. The weapon will be behind the building in an access area. There are a few areas to use this but luck will come in, just keep it at the ready for when you see some enemies bunched up.Strike Force missions:Shipwreck:Destroy CLAWS (x2) using only soldier- You may be lucky and find a soldier with a SMAW, if not, there are a few enemies using RPG's, try take them down and steal their weapon. Takes a few shots from an RPG to kill them, but explosives are probably easiest. An LMG may also work but takes a few rounds. (Most of the soldiers have a grenade launcher/noob tube on their gun)I.E.D.Eliminate enemy personnel (x3) while they are planting IED- If you use the Quad Drone and stay ahead of the trucks. The one's you're looking for are enemies running then standing still in the middle of the road. Shoot them when you see them crouching. Not too hard but may require a couple of play throughs.Second Chance:Eliminate enemy personnel (x5) by exploding vehicles- This one can be annoying I grant you. As you check the locations, more and more enemies will spawn in. Once you have checked at least 4, switch to the VTOL and find some vehicles. Then be patient and wait for them to pass by vehicles.DispatchComplete the mission in "tactical view" only-This one will be MY actual advice, since the challenge guide isn't very helpful w/this one, and this is the hardest one to get tactical view, So as you begin immediately go into tactical view, direct your troops to the left of the direction you start off facing, go through that alleyway. Since the AI is retarded, make sure you mark each soldier individually as you see them, only move them up once you KNOW every one is dead, then kill the turret. Next, slowly take out the ASD units one by one, if your lucky the AI will be smart and kill 2 with one rocket, before you move into the open make sure the ASDs can't get you so easily then quickly take out the two sentry guns, next kill all ASDs left after placing the hacker to move it along quicker. Hopefully your AI will be smart the first time as mine was utterly stupid and I had to retry at least 3 times before they said to themselve "Huh, I wonder what would happen if I kill the ASD units?"If you followed this guide, all the hard challenges should be done.there are more video guides coming by the user who made the challenge guides, so watch for them, again I DON'T OWN ANY OF THE GUIDES!!! I am simply spreading them around