Sliently kill grunts
if u are ever in a room full of sleeping grunts(the little blue guys) you can kill them by hitting them with your gun.
Kill elites
to kill elites (the big armored guys) hit them in the back of the head or hit the middle of their of their forhead
Kill own team mates with out people knowing
when u're in a tank, get your teamates and get them on the tank, while in a quite tunnle go clost to the wall and shoot, they will all be killed
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