Okay… I’ve been playing this a little while now, and I’ve kinda managed to get a single-class focus going, so that should be appropriate for this thread. I’m… okay with it; I can’t boast the experience some people have had, but I can go in-depth here.
A lot of people don’t seem to roll assassin much. And yet I’m specialising in it. So, saying that, maybe my input will be useful! ~
So some tips I’ve put together, in an arbitrary order of importance:
1) Your greatest weapon is your jump-pack. You are the most maneuverable class, but possibly not the fastest; from memory, the scout runs only a m/s slower than you at top speed, but has fancy boosts and kicks and chops and so they are generally faster than you on average…. on /land/ that is.
A quick jump (a single tap of the space key) will charge a jump that speeds you up to 45 m/s, so, pretty fast. With that said, you should generally spend as /little/ time as possible on the ground. You will also have very good air-control, so you should be moving and jumping from perch-to-perch like a ninja. Flying, even. A fully-charged jump can get you almost across an entire map, and extra adjustments with the pack in midair means you should be able to move from any one spot to another in one or two movements.
2) Do not expect to do direct damage. Your needlers’ damage is miniscule, on-hit. Still pump as many as you can into your target, but remember the real purpose is to get a stack of ten toxins into them. These are going to burn away at an enemy’s health, keep their shields from recharging, all sorts of mess. But you’ll die if you try to go one-on-one with anything from the time it takes, unless you’re good with your jump pack and can keep firing without getting hurt. (Which is also recommended over diving in and swinging your blades around.)
The way you /can/ do direct damage centres around both your positioning and those toxins, and your two abilities at that. Up close, the ambush blades can do a /lot/ of damage, and you can close in from a short range with the ‘engaged’ attack. (Locked-on, like the saber dash. Recharges after a second or two.) When you’re close, the knyphoon (‘r’ key) can take even the biggest classes down by 50% or more health, but that’s only if every hit lands. Try not to knyphoon a moving target while you’re standing still.
Catalyze Toxins, on the other hand, is used to bring down a poisoned enemy at very low health. You use it mostly to kill a running target before the effect wears off or before they grab health, but you can also quickly kill an assailant before they kill you, in a pinch. Do NOT use this ability for anything other than killing someone. That would be next to useless.
3) Cloaking is cool. You use it to either get in, or get out, or confuse a big guy. Cloaking and running for health /will/ save your life on many occasions. Cloaking and jumping into an encamped opponent (gunners and shockers) will normally kill them, using the blades, and cloaking to get around a tank you damaged (especially while he puts his shell up) will probably give you the edge you need to take them down solo.
4) The troll bomb — I mean, Panic Bomb, has a specific use. Don’t pop it at a single guy; that wastes your time when you could be pumping in more needles. You should use it in a large firefight, and hope that a pair of your enemies attack each other. If one kills the other, you’re awarded with the kill, as well as a well-deserved sense of smugness.
So to sum up, your job is very much spreading chaos and taking out HVTs. Snipers are top of the list, since they’re bad for your team and heavily disadvantaged against you if you put your skills together right. Always stay in the air; as soon as you touch down you should be charging another jump to a better position. In the air you can’t be bombed easily, and you can swoop down on your target by holding shift. You want to jump away quickly if things get too hot, and surprise your enemy if you want to take them out. You’re best off moving around and shooting needles for fast classes, and using the knyphoon on slower ones. And since blazers can counter all three of your strengths, you’ll want to use some mixed tactics to bring them down.
And please correct me if I’m wrong, those in a better position to speak. This is how I play assassin, and how I rack up a good number of kills even though I’m a support class. But at any rate, I hope this helps!