Mission: Countdown

Mission: Countdown Alpha, Mission: Countdown Bravo, and Mission: Countdown Charlie are repeatable main quests in Fallout 76 that triggers the dropping of an intercontinental ballistic missile on a map location selected by the player character.

Quick walkthrough
Before starting this quest you will need to acquire at least one nuclear keycard and the decrypted weekly launch code for the silo bunker that you intend to enter.

Once you enter a silo bunker (either Site Alpha, Site Beta, or Site Charlie), be prepared for many robot enemies. Bring energy resistance gear and energy weapons. Eventually you will need to enter a high radiation zone.

Upon completing this quest, the player character will be prompted to select a blast zone target location within Appalachia for the nuclear missile. Some lower-level areas located in the western portion of Appalachia are considered to be within a "protected zone" and cannot be targeted. If Fissure site Prime is targeted, the Scorchbeast queen will be spawned and the Scorched Earth quest will begin. Targeting other locations will spawn higher level versions of whatever enemy is normally present in that area.