Level 79

Total Experience Required 3,163,200 [confirmed]

Level 100 progress: 46.34%

This is roughly:
Killing 10,544 people in Warzone, or...
Killing 10,760 people in Execution, or...
Killing 8,936 people in Wingman, or...
Scoring 2,259,429 points in Guardian, or...
Scoring 6,876,522 points in Annex, or...
Scoring 4,162,106 points in Submission.

Horde (TU4)

Completing 15,816 waves on Casual, or...
Completing 10,544 waves on Normal, or...
Completing 7,908 waves on Hardcore, or...
Completing 6,327 waves on Insane.

Or a combination of the above. Have fun!