Level 74

Total Experience Required 2,512,081

Level 100 progress: 36.8%

This is roughly the same as:

Killing 4,187 people in Warzone, or...
Killing 4,273 people in Execution, or...
Killing 3,549 people in Wingman, or...
Scoring 897,172 points in Guardian, or...
Scoring 2,730,523 points in Annex, or...
Scoring 1,652,685 points in Submission.

Horde (TU4)

Completing 6,281 waves on Casual, or...
Completing 4,187 waves on Normal, or...
Completing 3,141 waves on Hardcore, or...
Completing 2,513 waves on Insane.

Or a combination of the above. Have fun!