Level 20

Total Experience Required 49,655

Level 100 progress: 0.73%

This is roughly the same as:

Killing 83 people in Warzone, or...
Killing 85 people in Execution, or...
Killing 71 people in Wingman, or...
Scoring 17,734 points in Guardian, or...
Scoring 53,973 points in Annex, or...
Scoring 32,668 points in Submission.

Horde (TU4)

Completing 125 waves on Casual, or...
Completing 83 waves on Normal, or...
Completing 63 waves on Hardcore, or...
Completing 50 waves on Insane.

Or a combination of the above. Have fun!