Level 85

Total Experience Required 4,073,479 [confirmed]

Level 100 progress: 59.68%

This is roughly:
Killing 13,579 people in Warzone, or...
Killing 13,856 people in Execution, or...
Killing 11,508 people in Wingman, or...
Scoring 2,909,628 points in Guardian, or...
Scoring 8,855,390 points in Annex, or...
Scoring 5,359,841 points in Submission.

Horde (TU4)

Completing 20,368 waves on Casual, or...
Completing 13,579 waves on Normal, or...
Completing 10,184 waves on Hardcore, or...
Completing 8,147 waves on Insane.

Or a combination of the above. Have fun!