He's the best in all cave missions where he can bottleneck enemies in tunnels, for the simple reason that it's the only class that can cover 2 sides of the tunnel (or even 3) at the same time and he can easily rotate through 3 sets of weapons that can likely deal damage from good safe spots. Once you have a vehicle you can use it too, and the turrets will rebuild in the background. It can also provide powerful firepower that will make him handle these with ease.
However, he's also the worst if you have to fight in open and large caves without an option to retreat to tunnels. Unfortunately, there are 2 missions in the main campaign that fall into this area and these are really hard to handle, although you can make your chances better by using better gear, specifically DLC2 ones if playing in Inferno.
The basic strategies to handle cave missions are:
- bottleneck enemies in tunnels, preferably in ones where there's just one end or where there are few to no chances of not getting all enemies coming from one of the sides
- equip 3 sets of turrets and use them wisely so that you always have one set covering the tunnel where enemies will come from, or spread them on two sides if necessary, and always have one rebuilt and preferably set up to use when the one running is exhausted
- correct use of vehicles will help with movement, either to progress, run away or shoot in all situations
- you need knowledge of enemy spawn points and waves, and what triggers them. The AR is the knowledge and brains class and all this is a lot more important in these missions as you need to prepare turrets and apply the right ones to handle what will be coming. Scouting with the WD in easy or normal can help in this.
- driving the Depth Crawler will be essential, even in walls and ceilings (this does drive me nuts as I get lost with the inverted controls 😁), but it has been greatly improved from 4.1 so it's not that hard to take advantage of it. Be careful however where you travel it's not unusual that due to clipping issues you end outside the map area without any chance to return and the mission is ended (very common on DLC1-11 for instance)
- there's no way to avoid unexpected damage through walls from enemies, either spider webs, cosmos flamethrowers, ants acid, Araneas grabs, or whatever craziness will happen. These "happenings" are a trademark of Sandlot EDF games, and even though they're less prone to happen in EDF 5 they're still common
Turrets
Turrets are awesome on EDF 5. Not only do they rebuild automatically in the background when they end (or you force that) there are 2 new ones that can be awesome.
FZ-GUNs - If you can use them, these are by far the best. They last a long time, stun enemies and hit several at the same time with the same turret, they do decent damage, you can have decent numbers of them with up to 5 of the best one, they rebuild fast (although it's true that once fully upgraded all turrets rebuild in the same time, 29.4 secs) and won't damage vehicles if installed on them. They do have issues as they will damage and stun you, vehicles and NPCs if installed on terrain, but will just damage NPCs if installed on vehicles (or you if you're outside the vehicle). If correctly installed near a spawn location they can freeze and kill the whole group of enemies.
ZEX Launcher - The ZEX Launcher is dangerous as it can easily damage extensively you, your vehicles and NPCs due to the large blast area. However sometimes they're awesome as they not only damage multiple enemies with the same blast, they project them hopefully away from you, although it's not unusual to have them sent towards your location particularly in the case of silver spiders. They won't kill any enemies in one shot, but manage to keep most at bay from you and work nicely against frogs and cosmos. However, they are pretty bad in open caves ( for instance they're a nightmare to use on mission 86 Secret in the Dark ) as the chances of damaging you and the NPCs become pretty big and can be dangerous too in missions with intricate caves as they will target enemies that can't be reached but technically are closer and can hit you (as it happens in DLC 2-6 Underground 3 ).
ZEXRs and ZERA - These are your bread and butter turrets. Not total problem solvers, but they provide all-round stellar service. Their biggest plus now is that they won't ever damage you, your vehicles or any NPCs either if they're on the ground or installed in vehicles. Unfortunately you can only have one set of them 😞. Their biggest problem is dealing with high-powered enemies and short duration. Most of their siblings are toys (ZE-GUN10, ZE Sniper).
ZE Blaster - These are the "worst" of the bunch. Although they are still good, they're very slow at tracking enemies and due to the small spaces where you'll usually have to use them, they are not very efficient. It's very usual that they're hitting and stunning an enemy, then another jumps over them and they lose a long time tracking either the last or the new one. They do work nicely on open caves though so they can make your life a lot less miserable in some missions ( 86 Secret in the Dark 😰 ). These need experimentation as I had a lot of bad experiences with them and the other 3 will generally work better.
Vehicles
Depth Crawler - no choice here but there are differences between the ones you can have. The Depth Crawler IV Custom and V are almost equal, with the latter being faster, with more armor and slightly better weapons, but be careful with the Rapid Bazooka as it can damage the DC if you accidentally shoot NPCs or enemies very near you. The Depth Crawler IV is interesting if you have many tunnel exits or silver spiders as the cannons are slower but do a lot more damage per shot, and you risk no self damage unlike with the Rapid Bazookas. The Depth Crawler S Range Custom has an interesting flamer weapon but it gets empty pretty fast, and it's just available up to tier 52 which is pretty basic and difficult to be useful beyond hardest.
The machine gun is nice but imprecise and shooting angles are sometimes weird and make precision aiming difficult. Lots of ammo on them though.