So this achievement just dropped for me yesterday. Man, was it a journey. I never thought I'd do it, but I have and I'm here to tell you how I did it.
My apologies, BTW, for how sloppy this list is. This is a very complicated achievement with many parts. All I can offer is a random grab bag of tips and tricks.
1) 50 Re-Ups. There's no real substitute for just putting the time for this one. My Xbox stats say I've put in about 76 days into this game. That gives you some idea of the time commitment involved.
There are ways of maximizing your xp yield. First of all, remember to mark everything you see. Even when you don't get the kill, marking a target that is killed gets you an assist and an xp boost. It's generally just good practice as well and will help win you matches. Secondly you should realize that not all kills are created equal from an xp standpoint. Headshot kills and executions are king. One playstyle to maximize you xp gain is to use Marksman, Veteran or Anchor classes, and/or other classes that have a big crit damage boost to get many, many headshots. The Marksman ult is particularly useful for this. So is the Veteran's, particularly once you dump his loadout lancer for a retro lance or longshot. Anchor's Bullet Chain card is also good.
As for executions, it is important to utilize the importance of stuns. There are a variety of ways of doing this. The Infiltrator's Cloak ult is a good way to get executions. The Nomad's Fear ability is another; it can be used to create more Fear with the Faze card, so you can chain executions together over and over. The Gunner's Concussive Explosive card is a good 4 second stun at level 6. The Slugger comes with two stuns; one from flashbangs, which you should be able to regenerate with a perk; the second with the gold Impact card, allowing you to stun drones with an active shotgun headshot.
2) Inconceivable Campaign. Start a New game + that allows you to bring all your Jack upgrades over. Also be sure to turn the Ability cooldowns to "Fast" so you can spam them one after another. I also like to set the ammo to "Double" and to turn on bobble heads, which makes landing headshots at a distance way easier. Personally, I found the best abilities to be Flash, Shields, Cloak and Stim. Make sure these are fully upgraded and respec if they aren't.
With these abilities, Incon campaign is pretty easy. Use them liberally. You can cloak and run around executing everything. You can shield yourself and headshot enemies. Remember that your companions like Del and JD will often be carrying power weapons. Hard aim them with the left trigger and a prompt to trade weapons should come up. You should have a longshot or a lancer gl whenever you need it. If you turned double ammo on in the settings you should never run out of ammo either.
Fully upgraded Flash is a good way of dealing with most bosses. It will freeze them in place, during which they'll take triple damage. The Snatcher at the end of Act II, chapter 4, in the Mines is one of the toughest bosses in the game. I simply flashed him and killed him with one quick dropshot. Nothing.
Special note on the Matriarch at the end of Act II. Go into the fight with as many frag grenades as you can carry. At one end of the arena you should find two ice cannons against the wall. Use those to freeze the Matriarch in place and then grenade tag her in the back. Rinse and repeat about four times and this fight should be over.
3) Mastering hives and horde maps. Since there are 37 horde maps and 32 hives, writing up a guide on each Hive and Horde map would require the space of a book.
a) First, Escape. For Hive guides I refer you to Madokon's Youtube page, one of the few channels covering Escape in depth.
https://youtube.com/c/Madokon Another good channel is turnerburner922. He's arguably the best Escape player in the world, holder of the top time on the global leaderboards on at least five Hives, and the holder of a top twenty score on virtually all of them. When the Line, one of the most difficult and unusual Escape hives, was giving me trouble, I watched his videos of soloing it, which helped me devise an optimal strategy.
https://youtube.com/channel/UCUJeqGVmo-XSap4AKRAuCAwhttps://youtube.com/playlist?list=PLLOsBhDQD5Lw1Ih_QQY8kxxMC...Beyond that, here are a few miscellaneous comments on Escape from memory. First, the best Escape classes are those that don't need much in terms of pickups like Blademaster, Protector, Nomad and Brawler. Combat Medic is a good partner for melee focused classes. Anchor is also very strong. Beyond that, class choice is situational based on the pickups available. Marksman is quite strong on Ice Queen, Lethal Engagements and the Split. High level Mechanics with the Custom Robotics, Personal Defense and Robotic Porting cards can thrive on the Detour and the Malfunction because of all the DB weapons available. Tacticians are a big plus on Hives with the ammo starvation modifier like the Gauntlet or The Minesfor example. Some maps like Melee Brawl and the Line have enemies that fire freezing bullets, which makes the Gunner's freeze damage resistance card really powerful.
A little known fact: the Pilot's Rear Armor card provides Venom Resistance as well, making it a very strong choice on Fast Venom Hives like Venom Run, or the Blight.
b) Now, onto Horde. Starting off, let's just say that I mastered virtually all the maps playing with randos. It's possible to do it. If you have good people to play with, then fine. You can do them in 50 waves or in Frenzy. Both count. You can do only wave 50. That apparently works as well.
A few remarks on class balance. As you play and learn each map, including the ideal places to set up your base, each playstyle and spot will call for a different mix of classes. This isn't an exact science though. You want a mixture of DPS, crowd control, utility and survivability. Generally speaking, to take one example, having an engineer, a jack and a combat medic in the same party will put a lot of pressure on the remaining two party members to kill things. Best to kick the jack or the combat medic. Having an Infiltrator and a Blademaster gives you a lot of close quarters dps, which means you might be better off adding a ranged dps, like a Demo or a Tac. IMHO the dps the Demo provides is difficult to replace, although it can be done with all five players working together. Anchor is the best all around class. Every squad in every situation benefits from an Anchor, because it gives as good mix of damage, utility (the Harness card gives stim) and survivability. If you have decided to set up in a small, confined area, like the Maintenance section on Lift, the healing speed boost of a Combat Medic could save your team from wiping.
BTW, Hollowstrife's Youtube channel is a great source on Horde, including details like fortification costs for Mechanics and how this is effected by the Efficient Fabrication card.
https://youtube.com/channel/UCh4oc-uR9JWe8iuboMKSPIAMiscellaneous remarks on individual maps. Most are pretty straightforward, like Blood Drive and Overload. The most difficult ones in my estimation are Regency, Allfathers, Training Grounds, Foundation and Pahanu. Regency is hard because the taps are difficult to defend. Combined with the Power Drain modifier, this makes gathering enough resources to build a viable base very difficult. Bring a Jack with a maxed Optimizer card and build him a forge early so that you don't have to rely on the taps. Ditto for Foundation.
If you don't wish to master a map the normal way, consider using a Tac-Demo team to speed run a map. Start at level 50. The tactician needs a maxed interrogation card and perhaps Recharge Bounty. This will allow him to mark every target within a large area instantly by meatshielding a drone. The Demolitions player can then kill them with his ult Artillery strike if he has a Spotter Support card. The tac's recharge card should bring back the ult immediately, as should the demo's Confirmed Kill card. Repeat as needed. The Tactician's role is just meatshielding drones so equip flashbangs from the fabricator.
Other crowd control classes like a Nomad or Gunner can provide support as well.
Tactician build for this method: Interrogation, Grenade Pouch, Recharge Bounty.
Demolitions: Spotter Support, Razor Hail, Confirmed Kill.
4) Leveling Classes. Just remember to do your Dailies. A lot of players like to level by speedrunning the Surge on Insane difficulty. This does work. Act one of the Clock is also a popular speedrun.
It used to be that the first piece of advice I would give would be to buy xp boosters from the store and to utilize free xp weekends. Since then the Coalition added a permanent 300 percent booster, applying to class xp as well as regular xp. Leveling has never been easier.
Beyond that, the same methods for gaining regular xp also get you class xp, so look at section 1).
Addendum: I forgot to mention how broken the melee classes are in this game. There are a number of glitches associated with melee cards that result in exploits. For example, the text of the Striker's Blunt Instrument card is incomplete. It says it gives 130 percent bleed damage when using the Breaker Mace; what it doesn't mention is that firing a weapon and then switching to the Breaker Mace right afterwards can put bleed damage on any target no matter the distance. Personally, I find this a little unwieldy for drones and juvies, but it's a good way of killing bosses and heavies across the map.
I learned about this glitch, btw, from Cherry Quench's Youtube channel. Here is the video.
There are similar glitches in the Protector and Blademaster cards. The Protector's Gnasher M45 and the Blademaster's Brutal Claw and Gnasher Mastery cards not only effect the weapon damage mentioned in the text, but also melee bleed damage inflicted while the weapons are equipped. This means that if you have a max level Gnasher card equipped, the Protector gets another 60% added to his melee bleed damage if he just holds the Gnasher in his hands. The same for the Blademaster. Just holding the weapon gets the bonus damage applied to melee bleeds.
This glitch is way better for the Protector than the Blademaster. The Protector's Gnasher card is green while Brutal Claw and Gnasher Mastery are purple, so it's much easier to upgrade. For another, Blademaster needs to perk in Horde or to be in Venom in Escape to cause bleed damage, where the Protector causes melee bleeds right away.