How does one get combat bonuses in Tomb Raider multiplayer

tomb-raider-2013

Like Steadiness (+ Weapon Stability), Firebug (+ Fire Damage), and Hardheaded (-50% Headshot Damage) that accumulate in the lower-left corner, right of the clock symbol, and look like badges? Also, what are they called?

bonuses outlined in red
Outlined in red.

Best Answer

They are earned per kill. I don't know if you can manipulate which bonus that you get; the bonus that is earned may be at random. I don't know what they're called.

Update: At least the Heat sink (No Overheating) bonus can be obtained from cracking a crate. This bonus has a diamond-shaped outline unlike the other kill-streak bonuses.