Level 68

Total Experience Required 1,853,708

Level 100 progress: 27.16%

This is roughly the same as:

Killing 3,090 people in Warzone, or...
Killing 3,153 people in Execution, or...
Killing 2,619 people in Wingman, or...
Scoring 662,039 points in Guardian, or...
Scoring 2,014,900 points in Annex, or...
Scoring 1,219,545 points in Submission.

Horde (TU4)

Completing 4,635 waves on Casual, or...
Completing 3,090 waves on Normal, or...
Completing 2,318 waves on Hardcore, or...
Completing 1,854 waves on Insane.

Or a combination of the above. Have fun!