Level 12

Total Experience Required 18,523

Level 100 progress: 0.27%

This is roughly the same as:

Killing 31 people in Warzone, or...
Killing 32 people in Execution, or...
Killing 27 people in Wingman, or...
Scoring 6,616 points in Guardian, or...
Scoring 20,134 points in Annex, or...
Scoring 12,187 points in Submission.

Horde (TU4)

Completing 47 waves on Casual, or...
Completing 31 waves on Normal, or...
Completing 24 waves on Hardcore, or...
Completing 19 waves on Insane.

Or a combination of the above. Have fun!