If you want this the fastest way possible, the three shortest playlists are as follows:
- Wheels, wheels, and more wheels (3 missions on normal)
- Mixin' it up (3 missions on normal)
- Heavy anticipation (3 missions on legendary)
If you really can't bare legendary and want the easiest method possible (regardless of time) do the first two I listed above and as a third, do the easy or normal campaign playlist
This shouldn't be too hard to get, however, "Heavy anticipation" might be tricky for any beginners. On the normal missions, for the most part you can just run through the enemies to minimise the time. For heavy anticipation, you're going to want to take your time for this one seeing as enemies are tougher and much more aggressive.
Tips for Heavy anticipation:
Crow's nest, Floodgate and The Covenant are the three missions you need to complete. The first two are pretty quick and straightforward. However, The Covenant is where it gets tricky. In my opinion its the hardest mission in Halo 3, especially during the Hornet sections. So here's some advice:
- If you can skip a fight, then skip it. Most battles can be ran past if carried out swiftly and effectively. This can be done most easily on Floodgate and I managed to complete this level in 10 minutes using this method.
- For the two scarabs in The Covenant, make sure you take out all the banshees before going for the scarabs. This will make the fight MUCH easier.
- Play on co-op if you can. Its a lot easier than on solo.