Level 83

Total Experience Required 3,756,493 [confirmed]

Level 100 progress: 55.03%

This is roughly:
Killing 12,522 people in Warzone, or...
Killing 12,778 people in Execution, or...
Killing 10,612 people in Wingman, or...
Scoring 2,683,210 points in Guardian, or...
Scoring 8,166,290 points in Annex, or...
Scoring 4,942,754 points in Submission.

Horde (TU4)

Completing 18,783 waves on Casual, or...
Completing 12,522 waves on Normal, or...
Completing 9,392 waves on Hardcore, or...
Completing 7,513 waves on Insane.

Or a combination of the above. Have fun!