Progress through the level normally until you reach the bridge with the ghosts. You can do the normal strategy of pressing the button or do the grenade jump in the ghost to get across the gap. The rest of the level excluding the end fight is driving, and I recommend watching a video for the level to learn the driving/OoB because there are a bunch of triggers you need to hit to progress through the level.
For the last fight rocket the two elites standing by the hologram and then grab the sword and kill the other two elites with it. Make sure you don't use all your rockets so you can carry over your sword to the next level.
Get the BR from ODST, kill the closest turret and any Grunts in your way, do the OoB trick. If a sniper spawns near the distant turret at the temple, fire a rocket at it as you're going up, it'll let you walk straight to the trigger. Otherwise stick to the right to avoid being sniped.
Head over to the trigger then walk over to the Ghosts. The Wraith won't spawn and you'll have skipped a lot of heavy fighting. Destroy the other Ghost to prevent it from being used. You can either launch to the waterfall, launch to the side of the waterfall, launch to where the Wraith would be, or extend the bridge (slowest).
Next area is a pain, a lot of Shade turrets and random Ghost spawns. If you manage to get through all that, get out and retrieve Envy skull. Drop down into the room below and get sword. Nade jump back up and sword cancel off the stealth Elite to get over the wall.
Kill the waterfall Jackal, sword fly to the Elite in the cave on the left (don't kill him or you'll spawn the Drones). Cloak and walk to the next area.
Pick up the 3 frags if you're doing a full game run, sword fly to the Jackal snipers on the roof. Drop down, spawn the honor guard Elites, stealthily dispatch them to prevent more from spawning.