Level 25

Total Experience Required 82,884

Level 100 progress: 1.21%

This is roughly the same as:

Killing 139 people in Warzone, or...
Killing 141 people in Execution, or...
Killing 118 people in Wingman, or...
Scoring 29,602 points in Guardian, or...
Scoring 90,092 points in Annex, or...
Scoring 54,529 points in Submission.

Horde (TU4)

Completing 208 waves on Casual, or...
Completing 139 waves on Normal, or...
Completing 104 waves on Hardcore, or...
Completing 83 waves on Insane.

Or a combination of the above. Have fun!