Level 86

Total Experience Required 4,236,742 [confirmed]

Level 100 progress: 62.07%

This is roughly:
Killing 14,123 people in Warzone, or...
Killing 14,411 people in Execution, or...
Killing 11,969 people in Wingman, or...
Scoring 3,026,245 points in Guardian, or...
Scoring 9,210,309 points in Annex, or...
Scoring 5,574,661 points in Submission.

Horde (TU4)

Completing 21,184 waves on Casual, or...
Completing 14,123 waves on Normal, or...
Completing 10,592 waves on Hardcore, or...
Completing 8,474 waves on Insane.

Or a combination of the above. Have fun!