If your only progression system is challenges at least only put challenges that entice to play Better!

“Stop Killing Sprees” what actually means? let the enemy kill you a bunch of times."
“Kill enemy spartans trying to return their flags” what actually means? I am going to drop the flag mid way and camp.

It is bad enough that people don’t play objectives because they want to do challenges. There are a bunch of challenges that actually entice to play bad.