For all the people out the that wants to complete all challenges or just want to unlock a fancy calling card, there is a section called Special Ops, pretty sure everyone knows about it, in there you'll see quite a few Unknown challenges that you have to discover by yourself on what to do, i'm sure many of you have completed a few and are know what to do, but i figured would be good for everyone if we have a list of them in here, keep in mind that these challenges are the ones that either i already complete or i'm trying to do, hence i already know what to do, with them ill put some tips to make your life easier, wish i could make a video out of it, but i lack the program to do it lol, the order of the list will be on what i think goes from the easier to the harder challenge.
Melee an enemy who has been plagued.
Tip: If you ever see an enemy with a special animated calling card of the biohazard symbol, all you need to do to earn this is kill them with melee
Melee an enemy without killing them, then survive for a minute.
Tips: Now, this one require some explanation, the "hit" has to be from the front, or the side, only with your fist, normally a back punch will result on a kill, but even if you manage not to kill them, it will not count, for a class setup, use dead silence, use either Phase shift or active camo, once in the match, wait until your ability has charged before trying anything, once this is ready, go look for a victim, punch it on the face, use the ability and run, go hide somewhere for a whole minute, you CAN kill in your hiding spot whoever tries to get you, but you still need to survive the minute, so keep that in mind, contrary to popular belief frontline is not the answer, play something like Hardpoint or Defender, something where you know where the fight is going to be and stay out of it.
Damage an enemy with 4 different weapons without killing them.
Tips: all 4 of them need to hit the same target, grenades count as a weapon, i recommend only trying for this when you find someone in a match that is not going to be a treat, for the set up, i recommend having the Type A and Oni (the normal versions) will be easier to control the damage output this way and have two flechette grenades, once on the match and when you find a good target, use Akimbo Type a to hit it once, if done correctly, you can throw a single grenade and get the hit marker, wait for a bit for the enemy to recover, meanwhile change to the oni, then tag him with it and finish it with another flechette, if done correctly the challenge completion notification should pop. you can kill your target aftewards
No Idea what Im doing
Get 100 kills using hailstorm with a optic, akimbo and quickdraw
Tips: 100 kills in total, not in a single life, you equip your hailstorm, with the required attachments and go nuts lol
Triple Slide Stop
Get 3 kills in a row using the last bullet in a clip
Tips: The challenge its easier than what the description says, you need to get 3 kills in a row but they don't need to be fast, get your favorite weapon, a shotgun does wonders, empty the gun, keep either one shot on a sniper/shotgun or less than 5 shots on any other weapon (yes, apparently 5 shot or less are considered last bullet on AR, SMG and LMG), kill someone, then repeat the process, as simple as that, do not get any other kill if isn't with the last bullet, if you find yourself having issues on Core, try hardcore.
Follow another FTL Rig into Phase Shift and kill them there.
Tips: although this one sounds easy, its more about luck, the chances of finding someone phase shifting while you have yours available are slimier than you think, anyways as the challenge says, when you see an enemy phase shift, you have to phase shift as well, then kill them in the alternate dimension.
Protect yourself and two teammates from a Trinity Rocket with a Dome Shield.
Tips: Like with the Phase Hunter, this is more about luck, as the challenge says, you need to wait until the enemy calls a trinity rockets, deploy your dome shiled (yes is going to save you in case you didn't knew), and pray that there is other 2 teammates inside, i recommend you to carry 2 dome shields and use the warfighter rig with resupply, also play with friends and let them know what is your goal, so everyone runs inside the shield if the trinity rocket ever happens.
How the ?
Kill an enemy by triggering an explosive with another explosive.
Tips: as the challenge says, this requires you to kill an enemy with explosive "A" by triggering that explosive with explosive "B", if you get the kill with explosive "B" it will not count, this challenge is about skill and luck, if by any chance you find a trip mine, there is a high possibility that there is someone camping with it so you want to destroy it with a grenade, and get the kill, since this scenario is hard to find, is better if you make your own trap, for this you need C4 and the howitzer (the ONLY launcher that counts for the challenge), of course if you feel skillful enough, you can always use C4 and another grenade, anyways you want to play something with an objective, domination is a great one, place you C4 dead center on the flag your team control, then go sit somewhere, you need to wait for an enemy to try to capture and that hopefully didn't even see the C4, use your grenade launcher and try to hit the edge of the circle, that should trigger the C4 and kill the enemy, check your kill feed, if done correctly the challenge will pop.
Get 2 headshot kills in a row with ricochet.
Tips: in a row by boucing the bullet from the wall, but is not time based, doesn't even matter if is not in the same life, as long as the two headshots are in a row. i recommend for this one Hardcore, it HAS to be with an energy weapon, use the R.A.W LMG with Ram servo (the most important one), speaker amp, faraday slug, stock and quickdraw, you are probably going to die a lot attempting this challenge so keep that in mind, once in the match, every time you see an enemy, shoot the floor near his feet, this is the best strat to be able to hit the head with ricochet, Domination is a good one, specially when the enemy is capturing the objective, 90% of the time they tend to lie down while capturing, this is the best scenario for you to get the kill.
Get 2 kills with one bullet while power sliding.
Tips: Check epic run, same strategy.
Get 2 kills with one bullet while wall running.
Tips: It can be done anywhere, but i highly recommend the next if you want to get it out of the way fast, use a shotgun, the banshee is what you want, have the extended range attachment and anything to keep it from going recoil crazy, play hardcore domination and wait until the map Frontier, all you have to do when this happens, is ignore your base flag and run to the enemy home flag, whatever you need to wall run or slide, kill as many as you can on the flag, you'll get the challenge done this way, since the shotgun is a oneshot kill in HC and the bullets do penetrate targets.
Earn a De-Atomizer Strike
Tips: well this one does require a lot of skill and map awareness, for weapon use whatever one that you feel more comfortable and have the Nuke perk of course, use silencer and enough attachments to reduce the recoil (Don't worry about extended mags), use the Mercenary rig with reactive armor and Man-At-War, this will give you enough bullets to earn it, if you still feel that the bullets aren't enough use scavenger, although i prefer Hardline for faster UAV,Counter and Advance, Use Ghost and Dead silence and DO NOT camp,more often than not you'll die this way, since when someone see you with a nuclear weapon sitting in the same spot, they will come for you, what i do is put a number in your head, in my case is often 10, go play the game normally until you earn that number of kills, then slow down, try to hold an area but don't camp in the same corner, you have to be in constant movement, always watching everywhere, this is why i prefer the UAV,Counter and Advance, so i know where my enemies are, you have to be aware of your minimap, not only to check on enemies, but to know where your team is spawning, wherever they are spawning, thats the side you want on your back.
The gamemodes that i recomend if solo, Tactical TDM: you dont have to worry about no one jumping over you and it becomes a slower game, TDM most new players play this first, if with a team, play Defender, have someone grab the ball while you kill everything that comes your way.
And those are pretty much it, 12 hidden challenges.