Level 4

Total Experience Required 3,310

Level 100 progress: 0.05%

This is roughly the same as:

Killing 6 people in Warzone, or...
Killing 6 people in Execution, or...
Killing 5 people in Wingman, or...
Scoring 1,183 points in Guardian, or...
Scoring 3,598 points in Annex, or...
Scoring 2,178 points in Submission.

Horde (TU4)

Completing 9 waves on Casual, or...
Completing 6 waves on Normal, or...
Completing 5 waves on Hardcore, or...
Completing 4 waves on Insane.

Or a combination of the above. Have fun!