Level 53

Total Experience Required 764,738

Level 100 progress: 11.2%

This is roughly the same as:

Killing 1,275 people in Warzone, or...
Killing 1,301 people in Execution, or...
Killing 1,081 people in Wingman, or...
Scoring 273,121 points in Guardian, or...
Scoring 831,237 points in Annex, or...
Scoring 503,118 points in Submission.

Horde (TU4)

Completing 1,912 waves on Casual, or...
Completing 1,275 waves on Normal, or...
Completing 956 waves on Hardcore, or...
Completing 765 waves on Insane.

Or a combination of the above. Have fun!