Level 67

Total Experience Required 1,757,767 [confirmed]

Level 100 progress: 25.75%

This is roughly:
Killing 5,860 people in Warzone, or...
Killing 5,979 people in Execution, or...
Killing 4,966 people in Wingman, or...
Scoring 1,255,548 points in Guardian, or...
Scoring 3,821,233 points in Annex, or...
Scoring 2,312,852 points in Submission.

Horde (TU4)

Completing 8,789 waves on Casual, or...
Completing 5,860 waves on Normal, or...
Completing 4,395 waves on Hardcore, or...
Completing 3,516 waves on Insane.

Or a combination of the above. Have fun!