Reach Challenges: Campaign Scoring

Sometimes there are challenges like Points Pyramid (score xx,000 points) that require you to turn on a bunch of skulls and try to rack up a high score in Campaign.  The skulls do things like limit ammo, increase AI dodging of grenades, turn off the HUD, turn off radar, upgrade enemies, etc.  The more skulls generally, the harder it is.  But it's something you have to do in order to get a high enough score.  The key here is that the flying levels are largely unaffected by skulls because you have infinite ammo and Banshees/Phantoms/Seraphs are mostly unaffected by skull upgrades.

• Long Night of Solace - Rally Point Alpha: This is my preferred level for picking up Campaign scoring challenges.  Alpha checkpoint will put you in the Sabre.  I play on Legendary, with all skulls on except for Iron, which gives you a score multiplier of around 15x.  You can actually play with Iron as well since I don't die in the time it takes to get the challenge, but just in case you do die, this save you from having to restart.  I picked up the 40k challenge in 7 minutes.  Note that on-line it only shows 32,100 kills since I think you lose your time multiplier if you quit out of the level early, but the challenge still pops and sticks even if your final score ends up below the target.
• New Alexandria: Same thing as above, turn on a bunch of skulls since you'll be in the Falcon and shooting down Banshees.  Concentrate on Banshees only and ignore the Phantoms, that way you won't get swarmed.  See where OD picked up the 40k challenge in 9 minutes.

I prefer the Long Night of Solace because the bad guys are easier to see, Banshees are "fire and forget" kills because the missiles lock on automatically, and it seems to a little faster.  Your choice, both are pretty easy.