Today I tried out the challenge feature on Halo Wayoint. Not on XBOX, but through the website. You can assign a certain challenge by what the goal is, if you want it on a specific map, if you want it to be Firefight, Campaign, or Multiplayer, level of difficulty and if you want the people you are challenging to have to put on specific skulls to get the challenge.
I created three separate ones today.
In the first pic you’ll see the parameters I set up for that challenge: 
As you can see you can add your own special name for the challenge. This one is for Campaign, killing 500 enemies on Oni Sword Base at Heroic difficulty with several skulls on. It only had a window of 3 hours to complete.
In the next pic you can see a challenge similar to the first one. Here you see which skulls had to be turned on for the challenge, as well as how many credits a person can earn by completing the challenge. You have no idea how many credits it will assign until AFTER you’ve confirmed the challenge. I’ve noticed that the shorter amount of time given significantly adds the credits one can earn by completing a challenge.
In the third pic you can see that three people (including myself) completed the challenge. I got first place because I finished it first. I thought that the person issuing the challenge couldn’t earn the credits but it turns out otherwise. So challenge away!
Now to further explain this all… In order to get the credits you MUST first log into Waypoint, either through XBOX, or online. ACCEPT the challenge. Then go play the game and get the challenge done within the time allotted. You will not see the challenge in the challenge screen while playing, so you’ll have to check online or go to Waypoint between games to check your progress. Note: It may take a couple of minutes after a game for your just finished game to upload to Waypoint and the stats calculated.
Once you complete the challenge, you won’t see anything that says you completed it, however at the end of the game you will see the credits add up. In the case of the 10K one, I had one of my friends check his credits before the game we expected him to get the challenge done. When the game was done the credits were awarded and he confirmed that by the total of credits he had, seeing that it had gone up by more than 10K (which included the other credits for performance bonus, slot machine, etc.).
If you do issue a challenge to your friends, be sure to let them know by a message on LIVE so they know about it and can accept it.
Have fun!
Update!
It looks like the most a challenge can get to is the 10K mark. I tried something harder than the challenge I made yesterday and it only got 10K as the reward.
You can only do 5 challenges at one time and you have to wait for the challenges to expire before you get the credits unless you can time it just right to finish the challenge when the challenge is about to expire. (Which happened last night).
So say you set a challenge to end in 24 hours. You could finished that challenge MUCH sooner, but you won’t get those credits until the challenge is done.
There are pros and cons to this. The con is that you could cap out on credits quick on a given day if all of your challenges end on the same day.
The pro is that if you are going to be away from your xbox, set your challenges to end while your away and you’ll earn credits even when you’re not playing the game.
That will come in REAL handy this Thanksgiving weekend since many may not be able to play as much. I plan on setting up challenges that will end on this Friday and Saturday just for this purpose.