Level 17

Total Experience Required 35,421 [confirmed]

Level 100 progress: 0.52%

This is roughly:
Killing 119 people in Warzone, or...
Killing 121 people in Execution, or...
Killing 101 people in Wingman, or...
Scoring 25,301 points in Guardian, or...
Scoring 77,003 points in Annex, or...
Scoring 46,607 points in Submission.

Horde (TU4)

Completing 178 waves on Casual, or...
Completing 119 waves on Normal, or...
Completing 89 waves on Hardcore, or...
Completing 71 waves on Insane.

Or a combination of the above. Have fun!