Level 84

Total Experience Required 3,913,417

Level 100 progress: 57.33%

This is roughly the same as:

Killing 6,523 people in Warzone, or...
Killing 6,656 people in Execution, or...
Killing 5,528 people in Wingman, or...
Scoring 1,397,649 points in Guardian, or...
Scoring 4,253,715 points in Annex, or...
Scoring 2,574,617 points in Submission.

Horde (TU4)

Completing 9,784 waves on Casual, or...
Completing 6,523 waves on Normal, or...
Completing 4,892 waves on Hardcore, or...
Completing 3,914 waves on Insane.

Or a combination of the above. Have fun!