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For raider specifically? Get into buildings as you're inaccurate as hell outside (though if you manage to land shots, you can decimate them even outdoors) and use your speed to your advantage since you're the only maneuverable class that works well indoors, you can basically dodge all day and deny areas and hold chokepoints and blow the !@#$ out of structures with ease. Also the shield pack means that you can micro it on when you realize that you're about to be hit, and then turn it back on so you can move around freely again once the nuking's done.
