The stage is set for an ambush. Your scout is up front behind a bush with a good view of the open field. Your tank destroyers and heavies are near hard cover with just enough poking out to get a shot. Your mediums are somewhere in between ready to exploit the coming breakthrough.
The enemy appears and a hail of cannon fire erupts.
The red blips on the minimap vanish as your allies start exploding all around you. Everyone who hasn't pulled back into cover is taking artillery fire and screaming for backup. The scout is flaming wreckage. What the hell went wrong? Chances are, your scout screwed up by "doing something."
VICTORY TO THE BIGGEST GUNS!
You run into a lot of heavy equipment in WOT. Many people like kitting out the biggest nastiest thing they can find with Gun Rammers, Vents, Vertical Stabilizers, and Blaupunkts, confident in their ability to roll forward into the most oppressive hail of fire and secure victory for their side, alone, because real tanks need neither cover nor backup.
I may have mistyped.
What I meant to say is you run into a lot of twisted burning wrecks in WOT. Many people like kitting out the biggest nastiest thing they can find with Gun Rammers, Vents, Vertical Stabilizers, Blaupunkts, and rolling into combat only to find time after time they are bled to death via a thousand paper cuts from unseen enemies or worse, tracked and obliterated by an artillery shell with more "dyno-might!" than a blaxploitation weekend.
This feeling of blood lust is understandable, perhaps it's even human nature when driving a multi-ton steel chariot, but it's not always the way to win the match. The percentage of matches won through sheer aggression is staggeringly low, and when they are analyzed later it's usually not the aggression itself that won the match but something else for another article to discuss. We're talking about spotting here: the largest gun is useless without a target to train itself on, and the three heavies anchoring the battle line alone are probably going to die horribly unless the other team makes an equally terrible blunder.
FINE! VICTORY TO THE SIDE WITH THE MOST T-50'S!
The T-50 (and T-50-2) are still some of the greatest active scouts available. Nightmares of these things buzzing back and forth in front of and even through your lines are common among tankers. The T-50 and tanks like it are the most active scouts relying on their speed to keep from being hit while using their standard view range and moving their point of reference to light up the enemy. It is, however, very easy to kill the opponent you can see and all but the most skilled drivers (and perhaps luckiest) end up as flaming wreckage sooner or later. What if you're not that twitch? There's another option available for you but you're going to have to give up something you love to do for half the match.
Lets do something stupid. Lets take a Medium Tank, scrap that Gun Rammer and put on a Camouflage Net, drop the Vertical Stabilizer and replace it with a Binocular Telescope. Keep the Ventilation. Lets take Sixth Sense for the Commander and load everyone else up with Camouflage skill instead of their other goodies. That's a setup for chumps obviously. It won't be as good a flanker or brawler as a medium should be and it will get splattered in the first encounter... or will it? Lets do something even dumber now, and not even fire the gun for the first few minutes.
"Mr. Nesbitt has learned the first lesson of not being seen: not to stand up..."
I am reminded of stories about HARM's (Homing Anti-Radiation Missile) from various wars. We don't have these in WOT but we do have muzzle flare. When you fire your weapon most of your stealth goes out the window for a few seconds and this is when many passive scouts are killed. The passive scout takes up a commanding position behind the soft cover of a bush or tree that covers the arc of their tank most likely to meet the enemy... and does nothing. Nothing is a thing you can do, and sometimes it takes more effort to do nothing than to do something. This is the focal point of this article of course.
When passive scouting you are doing something, just not with your hands. When you are certain you are unseen, and you are providing a visual to friendlies of tanks that would quickly end your game it is the perfect time to do nothing. Resisting the urge to fire in these cases is difficult, and the fields of Prokhorovka are littered with the still flaming husks of tanks that couldn't. The advantages of not firing, even when a penetrating shot is available, can be considerable. There will be plenty of time later in the match where opportunities to fire arise so I wouldn't suggest training your neutral Jing by going into battle unloaded, but at times you might benefit to remind yourself most mediums do not pierce frontal armor very well, and hitting weak spots at the ranges you will be spotting foes from is a crap shoot. There will be times you will spot a foe far away from the side giving you a perfect shot, but if the path before you is quiet it's safe to assume the enemy is hiding there just out of spotting range... until you take that shot.
Most Tank Destroyers and Medium Tanks can passive scout nearly as well as Light Tanks. A Camouflage Net and Binocular Telescope are essential tools for the job, and crew training in Camouflage and especially Sixth Sense can be invaluable as mentioned before. Heavies make poor passive scouts despite their sometimes superior view range by virtue of their size, but the biggest thing to remember is not giving up what stealth you have.
"... However, he has chosen a very obvious piece of cover"
There are other things to remember for this play style of course. When the match starts you'll want to pick a piece of visual cover on your side of the halfway point, preferably easy to get to from your starting position, and sprint for it. If you make it there, stop and do not move. If you do cross paths with an enemy scout double back and try to kill it before it gets the Artillery; your cover is already blown. Try again later. Once in position, verify the arc between you and the enemy approach is covered by the bush or tree and let your Camouflage and Binoculars kick in. At this point you're waiting for your team’s heavy hitters to catch up and anyone getting close to you will light up for them to shoot at. Don't fire your gun. Remember you're in soft cover. Soft cover is something that obstructs your view but doesn't really do anything to stop bullets. If you are seen you will immediately become the primary focus of the enemy team because: they know what you're doing; they hate it; and you're the closest, squishiest target available. What the hell have I gotten you into?
GIVE YOUR ENEMY PLENTY OF OPTIONS, MAKE THEM ALL TERRIBLE
You've resigned the first half of the match to stealing XP and credits from teammates so odds are good you've survived to the second half. The enemy should be doubly paranoid but down a few tanks, and now you get a chance to shoot people. If the enemy scouts are all dead and the rest of their team are possibly damaged, you have a bit more lenience in what you can pull off. A lone heavy is much easier prey, though depending on your own tank the window wherein you can spot them, fire, and still remain unseen is exceedingly narrow. Unless your hull down kung-fu is exceptionally good they will fire back at the tracers and probably hit you.
The more dangerous situation is of course when you're advancing and they're waiting. A moving scout has no benefit from binoculars or Camouflage Netting, and a stationary heavy behind visual cover can get the drop on you. (Think of a fat man in a ghillie suit!) Still, many teams at a severe numerical disadvantage can end up in a draw instead of a loss simply because the enemy was too paranoid to advance on them. “If detected, run away” still holds true. Take a snapshot if you're aimed and loaded sure, but get moving. If they're fast enough to catch you chances are actually catching you will be a bad idea for them. If they're slow enough to evade, you can lay another ambush farther back. In one on one tank battles in real life victory often goes to the first shooter. Make yourself that first shooter over and over again until the enemy tank is killed.
If you're defending a section of map, pick a place with several obvious pieces of cover. If possible hide behind one you wouldn't expect to find yourself behind if you were the enemy. In an open field with a single large bush it's hard to mistake where your attacker is. You want a place where you can slip from cover to cover unseen. If your distance to the attacker is right you'll be able to see them but they won't be able to see you, possibly even when you fire. They will see the tracer though, and re-positioning will be necessary. If you can see down the targets barrel they won't need a visual to shoot you: you know they're on target already. This doesn't work as well early in the match when you're spotting because the fire will be coming from several sources making it difficult to focus on one, but in this situation it's probably just you and there will be no confusion about the source of their pain. Being tracked while moving at high speed is always disorienting. Aim for the tracks first to cripple them and spin them around, then go for the easier flank shots at the engine and fuel.
When only a few tanks remain the choices are cover everything and risk getting picked off, or huddle together and risk being flanked. This is the situation you want to help create, and then profit from. The enemy will typically focus on the largest, easiest to hit threat and the choice often comes down to the scout flitting in and out of hard cover, or the heavy lumbering toward them. Obviously this is a position no one really wants to be in. The passive scout, due to spending equipment slots and crew skills on stealth and spotting items, will be at a deficit in traditional combat so use that stealth and range to soften the targets as much as possible before they get close.
Win the mind game, feel smug when losing
This type of tank is extremely aggravating to play at first. It takes some time to get it right, and even when you do you're still going to run into scouts better than you, bad luck, terrible teams and the like.
Once you get the feel for it you'll find you have more time to consider the matches Schwerpunkt, which is difficult to contemplate while dodging fire. You will be able to see openings before they happen based on the minimap and speed to them, or bolster a failing front. While perhaps not as intense as running an ELC AMX at full speed like an armored terrorist, it helps prevent the tunnel vision that usually accompanies intense combat, and makes the all important situational awareness easier to maintain.