First of, an introduction. I'm new to the forums (but not to the game

Without further ado, let's continue to the actual guide.

Info:
Ah, the L-TAG. Short for Launcher – Tactical Armed Grenades. Unlike in the singleplayer, where you could stick grenades in the wall and make awesome traps, the multiplayer variant just launches grenades which have to bounce once on any surface (wall, ceiling, floor, teammates if you are feeling sadist

The explosion has a lethal radius of about 1.5 meters at which it will deal 125 damage (insta kill, w/ Armor on it's 84) and a max radius of 6 meters at which the explosion deals 1 damage (derp). The fire rate is 40 RPM (44 RPM with rapid fire perk (NOT WORTH IT)), and it has to 're-cock' after every shot (much like re-bolting a bolt-action sniper rifle), this makes it important to make every shot count. The actual grenade travels at a slight arc and at a slow travel speed (35 speed), this, combined with the bounce-and-fuse forces you to lead your shots if you want to kill moving targets. It also has a proximity sensor that knows whether the enemy is friendly or foe, so when you shoot a grenade close enough to an enemy (pretty much a direct hit) it will detonate and most likely kill. The magazine size is 5(+2) with 10 spares (15 with Side Pack). The reload time is 3.0 seconds and 1.65 seconds add time, add times means the times it takes to insert a new magazine aKa the point at which you can reload cancel (by double tapping the weapon switch button) and start shoot again. Also, it has no attachments, so I will not dedicate a chapter to just saying: 'Haha, there are no attachments!'
Why this gun is [B]BAD in close range:[/B]
I'm pretty sure some of us have tried using the L-TAG in close quarters, without much succes. The reason behind this is the fact that the grenade has a built-in safety feature, it will not explode when near you (approx. 2-3 meters, I havn't really been able to test this because it seems inconsistent to me).
Perks:
What you need are perks that make you aware of enemies that are nearby.
ARMOR:
Air stomp: HAH, nuff said.
Threat tracer: Not needed, you will be at long range most of the time, so just skip it.
Proximity alarm: This is the perk you will want to be using. This makes you aware if enemies are nearby. Not really neccesary to get it up to level 3 because you get those awesome red bars around your radar

Armor enhance: Not very useful, you are going to be far away, and when the enemy is nearby, the time you can spend in armor mode is plenty enough to kill the enemy and get back to pwning with the L-TAG. (tips coming up btw)
Nano recharge: Also not useful because you are not going to be close enough to the enemy to PROPHET from this.

Detonation delay: Seriously? No!
Energy transfer: If you prefer to sneakily cloak, uncloak, kill, re-cloak. This is the perk for you. Not recommended.
STEALTH:
Stealth enhance: See Energy transfer...
Covert ops: Only useful for the third upgrade, louder footsteps help awareness. One of the best perks IMO.
Cloak tracker: NO, just NO! Not useful at all!
Tracker: BAHAHAHAHAHAHAHAHAAAAAA, no, don't use it...
Jammer: Also not good because you don't want to be close to the enemy, or lure the enemy towards you.
Blind spot: Quite useful, this hides you from radar and is possibly the best perk to pick. You'd be suprised to see how many people will walk right past you when you have Blind spot on. I lol'd so many times. *BEST*
Visor enhance: Nah, not good at all, you should not use the irons (even though they are incredibly bad-ass!). Skip it.
POWER:
Side pack: Not the best, not the worst. Ammo could be a problem if you begin, but after you get better, you will find you have got plenty already, not worth it.
Weapon pro: Alright I guess, reload is relatively fast and shouldn't be a problem seeing are there should be no enemies around. WP3 is useful when caught with your pants down.
Aim enhance: Not useful at all. Just ignore it. Your grenades are going to bounce off anyways, so why want to be accurate?
Loadout Pro: OH YEAH! This is the one to go with when you don't want to rely on pistols (they svck). What's better then 2 primary weapons? Oh, wait, women are

Rapid fire: Not useful, the firerate increases by 4 RPM.
Point fire enhance: Also not useful, see Aim enhance for the reason.
Mobility enhance: It could do if you like to switch positions alot, better to do it fast.
Retriever: Actually, not the worst pick seeing as you are going to be sitting at mid-long range most of the time. 2 and 3 are totally worth it.
Tips:
ALWAYS, and I mean ALWAYS, get to higher ground, it's difficult to get kills and it's even more difficult to do it on flat ground. Play private matches (with or without friends) and see if you can find you vantage points that overlook chokepoints (places where enemies funnel together, places where one grenade is able to get 2-3 kills >:)
Don't always expect to get lots of kills with the L-TAG, it's a support weapon and it's not designed for killing large amounts of enemies. You'll have to settle for the occasional assist.
Don't just randomly spam grenades, it will grant you very little kills. Just go in stealth mode and observe, see where the enemies are at, where they come from and base your shots upon that. I.E. When playing Crash site on Skyline, don't just spam grenades of off the roof like there's no tomorrow. Get into visor mode, tag some enemies, see where they are at. If they are controlling the crash site, look overthere, check how many there are so you can judge how many grenades you will need (IMPORTANT, or you'll run dry in no time). If YOUR team is controlling the crash site, make sure nobody gets anywhere near it. Look for shadows on the ground, most people don't have Stealth enhance (2) on, so if you see a shadow, aim infront of it, and fire.
To further look into the grenades needed for targets. Let's get back to our crash site shall we? If you see targets that are cloaked (look for shadows on the ground!) or that are not in Armor mode, you will just want to fire 1 grenade down range, if it hits, but doesn't kill them, there should be team mates ready to sweep him up. If the guy IS in Armor mode, fire 2 grenades down range, he is easier to hit due to slower movement speed. And 2 grenades should kill the guy no problemo. If it doesn't your team mates will clean up.
*I might add more tips over time, so be on the lookout for edits*
My class:
Demolitions:
Scar Reflex Grenade launcher
L-TAG no attachments (there are none)
JAW
Proximity alarm (for situational awareness)
Blind spot (for not being seen on Maximum radar)
Loadout pro (for the extra primary)
Bob's class:
L-TAG
A pistol
Proximity Alarm x3(You know when they are near you)
Visor Enhance x3 (You tag and bag - and just in case they have Blind Spot see above^)
Retriever x3 (well kill streaks come easy this way)
To other people:
You are very welome to add your own class to the replies, and I will check them out, and maybe, just maybe put it in the guide. (chances of succes 99.9%

That's about it for this guide. Please leave some feedback. Hope it helps.
See you around!