In Supernatural, the Men of Letters’ bunker is a heavily-warded base that has been Sam and Dean Winchester’s home since season 8. Despite being warded against every possible enemy, a variety of powerful villains have breached the bunker over the years, beginning with Chuck revealing himself as God in season 11. Amara, Asmodeus, and Alternate Michael also managed to enter the bunker despite its supposed impenetrability.
Season 15’s “Galaxy Brain” revealed that the bunker’s warding had been irreparably damaged by Amara’s attack in season 11, which explains why high-grade baddies have had an easier time entering in recent seasons.
