From Destinypedia, the Destiny wiki
The Guardian fights across the outside of the Almighty and reaches the Starboard Landing
The Guardian enters Mineral Processing
The Guardian moves towards the tunnel but finds it clogged with debris. They backtrack and go back towards the other end of the room, where they find a large map with a Holographic image of Mercury.
The Guardian picks up a Solar Cell.
The Guardian finds an access port for the cell
The Guardian plugs the Solar Cell in and activates the processor. However, a large group of Red legion soldiers led by Purifier Vurst attack. After dispatching them all, the processor opens and the way is clear.
The Guardian fights through a number of Red Legion soldiers and reaches Sunside
The Guardian steps out into bare sunlight
The Guardian begins to take damage due to sheer heat of the sun's rays
The Guardian fights through several Red Legion sentries across the sun-exposed outside of the Almighty, and reaches the opposite section.
The Guardian encounters a series of platforms in a circular manner. After fighting through the Red Legion, they climb on top of it.
The Guardian fights through several more Red Legion soldiers inside the Almighty.
The Guardian presses forward and comes across a pair of accelerator tubes.
The Guardian battles the Red Legion before stepping into one of the tubes. They are then catapulted across the length of the Almighty. They are dropped into a room full of Interceptors.
The Guardian boards an interceptor and makes their way towards the main weapon. Upon viewing it, the weapon fires.
The Guardian progresses down onto the core platform.
The Guardian destroys one of the exchangers.
The Guardian destroys another exchanger.
The Guardian destroys the last exchanger.
The Guardian pushes their way into the main core system.
The Guardian picks up the cell and runs across burning hot coils. They reach the core and shove the cell into it. The core starts to overload and explode.
The Guardian sprints across the deck of the core while explosions rock the ship.
The Guardian reaches the hijacked Harvester with seconds to spare.