The campaign starts in 12 BG, hours or days after Roku's death. Sozin's Comet arrives in year 12, at 0 AG. The clock runs whether or not the party is looking at the sky. Advance it in downtime and in rumors, not only in cutscenes. If the players ignore a stage, the "if ignored" result happens in the world, and they hear about it from a vendor, a letter, a missing person, or a new flag on a wall.
DAYS 1-14
Official mourning. An evacuee list circulates. Rina vanishes from the Old Caldera Townhouse cellar shrine, possibly toward Hira'a. Sages argue over a funeral. Azane is already "helping."
If ignored: witnesses disappear into Azane's relief. Viro's log, Reki's tally, Jin's sighting, and Sora's attic guests become harder to recover.
MONTHS 1-6
Air Temples test children. Fire envoys visit with gifts. Yu Dao ordinances tighten. Dragon hunts spike.
If ignored: a child is listed. A dragon die-off worsens spirit storms. Bohai's street gets leaner. Hei Bai's woods are measured for timber.
YEAR 1
A White Lotus hiding route forms (or fails to). Dai Li fill more lake cells. The Northern Passage nearly goes hot.
If ignored: a regional war at Chenbao gives Sozin cover. More Lower Ring people vanish. Amara's route, if unbuilt, costs lives later.
YEARS 2-5
The coal fleet expands. Lambak shipments increase. The Guiding Wind is branded a threat. Some sages bend the knee.
If ignored: the Mandate becomes official policy under another name. Onaru signs, or is replaced. Palden's courtyard closes. Dalisay's dated operation is no longer a rumor.
YEARS 6-9
Temple "censuses" turn into watches. Colonies demand "security corridors." Polar spirits lash ships.
If ignored: Air Nomads are isolated and mapped. Fen's stole-list, or a better one, is complete. Travel between temples becomes a political act.
YEARS 10-11
Ruga's comet date leaks or is confirmed. Yeshe's hidden halls fill. Hesun sets a first-strike plan.
If ignored: the purge has logistics — ships, metal, lists, a night chosen in advance.
YEAR 12 / 0 AG
Sozin's Comet. Firebending is catastrophically amplified. This is not a trainable spell; it is an event (@Comet Empowerment as a world condition). If not stopped or diverted, Air Temples are hit to kill a still-unready Avatar and break the cycle's air generation. The Hundred Year War begins.
History can still diverge. That is the point of the campaign. A party that exposes the betrayal, hides the Avatar, breaks the Mandate, unites tribes and temples, or changes Sozin's position can move the ending. A party that becomes the Mandate can also change it, for worse or for a strange better.
OPTIONAL DARKER THREAD [Original, not hidden canon]
With no trained Avatar, a greater spirit hunger may gather: Koh becomes bolder, hunt-site spirits merge, or something older tests the borders of the world. This is not a later-era dark spirit walking in unannounced. Use it only if the table wants a spiritual doomsday beside the comet.
GM USE
At the start of a session or a downtime, name the year and one public event. Then name one secret event the party might discover. Keep Sozin's betrayal a secret unless a PC witnessed it. Do not skip to the comet because the party is mid-level; use Downtime Mode to cross years when the table is ready. If a PC is a child Avatar, downtime is how they grow into the clock rather than sitting still for twelve years of weekly sessions.