Level 97

Total Experience Required 6,234,451

Level 100 progress: 91.34%

This is roughly the same as:

Killing 10,391 people in Warzone, or...
Killing 10,603 people in Execution, or...
Killing 8,806 people in Wingman, or...
Scoring 2,226,590 points in Guardian, or...
Scoring 6,776,578 points in Annex, or...
Scoring 4,101,613 points in Submission.

Horde (TU4)

Completing 15,587 waves on Casual, or...
Completing 10,391 waves on Normal, or...
Completing 7,794 waves on Hardcore, or...
Completing 6,235 waves on Insane.

Or a combination of the above. Have fun!