Level 18

Total Experience Required 39,764

Level 100 progress: 0.58%

This is roughly the same as:

Killing 67 people in Warzone, or...
Killing 68 people in Execution, or...
Killing 57 people in Wingman, or...
Scoring 14,202 points in Guardian, or...
Scoring 43,222 points in Annex, or...
Scoring 26,161 points in Submission.

Horde (TU4)

Completing 100 waves on Casual, or...
Completing 67 waves on Normal, or...
Completing 50 waves on Hardcore, or...
Completing 40 waves on Insane.

Or a combination of the above. Have fun!