Follow the trail until you find some enemies around a human corpse. Examine the IFF tag then continue along the trail. Engage more enemies along the way until you find a soldier getting impaled by a promethean. Kill it then pick up the Promethean Vision. It will allow you to see enemy signatures through walls or obstacles.
Head through the fog. Aside from Promethean Vision, you can also pick up the Auto Sentry ability which as the name implies, deploys a sentry for a short period of time.
Continue along until you find another IFF. Examine it then move forth until you reach a wreckage. Follow the narrow trail until you reach it. Examine the IFF for a scene.
Before heading out, turn around to find a terminal. Once done, head outside and engage the group of enemies that will halt your advance. Continue forth until you find a group of friendlies under heavy enemy fire. Assist then and proceed as you clear the path. Fight your way to the door ahead and examine the interface.
While Cortana is attempting to open the door, man one of the turrets and defend the position until Cortana successfully unlocks the door. Go through the door and follow the passageway to reach the LZ. Clear the initial wave of guards and the reinforcements coming from the drop ship. Once cleared, stay put and wait for the allied Pelican to arrive. Ride it to reach the next rally point.
Clear the zone below then catch a ride with a Warthog or simply commandeer a Ghost. Clear all the enemy positions along the way. Be careful when you encounter watchtowers and Wraiths as they have some really heavy firepower. There's a parked Wraith in the next open large area. Make sure to use it to make your job a lot easier.
Fight your way until you reach the hangar. Whatever vehicle you're carrying, bring it inside as there is a large enemy force inside the ship. Clear all the hostiles to update your objective.
Enter the marked door and activate the console to reveal the Mantis. Pilot it and follow the onscreen instructions on how to control it. Continue clearing the path. Just make sure to take out visible targets at a distance, especially the plasma/laser turrets. Make your way to the elevator.
Exit to the deck and take out the jammers. Once done, keep clearing the enemies and taking out the drop ships as the weapons systems are slowly getting back online. In case you need a replacement, there are two other Mantis suits available in the area. The mission will be complete after successfully driving the Daidact out.
Defend the missile batteries