Bunker Buster Daily Missions in Destiny 2 are a new addition in Season of the Worthy. You can access it every day, as active bunkers in the game. At the moment, the only active bunker is in Sludge on the EDZ, but more will appear on the Moon, and Io, as the season progresses.
You can find them by heading to the bunker itself and heading to the large door behind Rasputin's main node that hangs from the ceiling. Legendary Lost Sectors will not be active until you complete the Bunker Buster mission each day. Interact with the door to open it, then head inside to find plenty of enemies crawling inside the main bunker. You will need to move from room to room, eliminating all enemies before continuing.
Some of the enemies will be champions, the most common we've come across so far are barrier and overload, so you'll need your seasonal artifact mods to be able to complete the bunker. Remember, these mods will only negate the effects of one enemy type, so make sure you have a few weapons that can take the different mod types, and have everything set up before entering.
When you go through the last room of the enemies, you will have to interact with a button to extend a few stairs to leave, then come back to Rasputin. There's not much, but you get Warmind bits to complete it, and a piece of Legendary Gear.
Usually it just seems to exist to give you something to wipe out to get back to a Legendary Lost Sector, but it could be tied to something bigger later in the season.
