H.E.L.M is a new addition to Destiny 2 for the Season of the Chosen. It will act a central base of operations as Guardians take on the forces of Empress Caiatl and her Cabal armies.
You can find the H.E.L.M by opening your Director and traveling to the Tower. On the main Tower map in your Director you will see a new green symbol that looks vaguely like the Eye of Sauron. We are not kidding, just look at the image below.
Click on this and you will load into the H.E.L.M. There does not seem to be a way to get there physically from the rest of the Tower, as all the internal doors are closed off.
H.E.L.M stands for Hub for Emergency Logistics and Maneuvers, showing that the Vanguard can really come up with a catch acronym. The H.E.L.M will also contain the War Table, so we guess they are technically the same thing, in a way.
The War Table will act as a central place to take on the Cabal forces, now being led by Empress Caiatl, in a new activity called Battlegrounds. These will take place all over the game’s various areas, and you will need an item called the Hammer of Proving. You will have to forge and socket Challenger Medallions from pillaged Cabal Gold for the right to take on her commanders in these contests. The War Table will also allow you to upgrade your hammer. We will have further detailed guides on all these aspects of the game when the update goes live on February 9.
Basically, the War Table and H.E.L.M would appear to be acting as the Seasonal Vendor during Season of the Chosen, as you can also get gear and upgrade a triple-tiered pursuit system there, which is pretty standard Seasonal Vendor stuff. We do not know if there will be an NPC present at this time.
The H.E.L.M will also house the Prismatic Recaster, which is making a return. Umbral Engrams are back, and you will be able to decode them at H.E.L.M. You will also be able to do things like managing your Vault and get items from the Postmaster, so it would seem that H.E.L.M will be acting as a true mini-hub for the season.