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🌋 Occurrences

35 occurrences16 calamities11 transformations8 eras & crises

An occurrence is a world event that stays on the map for several turns. The largest set is the Calamities, which ship with the Wrath of Gods DLC and strike on their own clock. Events start the era and crisis occurrences.

Calamity frequency Wrath of Gods

You choose the frequency at game setup. At least 5 turns pass between Calamities for each player, and the game balances both the calamity types and the players affected. A pending Calamity expires when it cannot strike within 3 turns.

Setting Earliest turn Frequency AI grace period AI skip chance Notes
None Calamities disabled
Very Rare +200% +300% between strikes no AI strikes before turn 30 2% Calamities will occur much later in the game and much less frequently
Rare +100% +100% between strikes no AI strikes before turn 20 5% Calamities will occur later in the game and less frequently
Default default — — no AI strikes before turn 10 10% There will be a balanced level of Calamities
Common -25% -25% between strikes no AI strikes before turn 10 15% Calamities will occur earlier in the game and more frequently
Very Common -50% -50% between strikes no AI strikes before turn 10 20% Calamities will occur much earlier in the game and much more frequently

Calamities Wrath of Gods

Drought

MajorGlobalNo duplicates
Trigger
  • Can occur from turn 10
  • 1% chance per turn to trigger
  • 1-turn warning before it strikes
Effects
  • -100% Farm
  • -100% Pasture
  • -100% Camp
  • -100% Grove
Terrain changes
  • Lake → Temperate (1% chance)
  • Temperate → Arid (1% chance)
  • Lush → Temperate (1% chance)
How it ends
  • Lasts 2–5 turns
  • 10% chance per turn to end, +10% each turn
  • Won't repeat while the Drought memory lingers

Plague

MajorGlobalNo duplicates
Trigger
  • Can occur from turn 20
  • 1% chance per turn to trigger
  • 1-turn warning before it strikes
Effects
  • -50% Growth
  • Units in territory: 50% chance/turn to be Plagued (3 damage/turn, -1 Fatigue, spreads on contact)
Characters
  • Characters: 10% chance/turn to become Infected
How it ends
  • Lasts 2–4 turns
  • 10% chance per turn to end, +10% each turn
  • When it ends: Infected characters recover
  • When it ends: Incubated characters recover
  • Won't repeat while the Plague memory lingers

Started byAt the Festival(as it opens)

Hurricane

No duplicates

Full strike

Trigger
  • Can occur from turn 10
  • 5% chance per turn to trigger
  • Requires Ocean on the map
  • Strikes a player-owned Coastal Water tile
  • Spreads across contiguous Water within 10 tiles
  • Also affects tiles adjacent to the affected area
  • 1-turn warning before it strikes
Tile impact
  • Units on affected tiles take 4 damage/turn
  • 20% chance to pillage each improvement on affected tiles
  • -100% base yields on affected tiles
  • +2 movement cost on affected tiles
  • -3 visibility on affected tiles
  • Unanchors ships on affected tiles
  • 20% chance to destroy vegetation on affected tiles (pillaging improvements)
How it ends
  • Lasts 1 turn

Mitigated

Strikes in place of the full calamity when the calamity is mitigated, and it has no trigger of its own.

Trigger
  • Strikes a player-owned Coastal Water tile
  • Spreads across contiguous Water within 5 tiles
  • Also affects tiles adjacent to the affected area
Tile impact
  • Units on affected tiles take 3 damage/turn
  • 10% chance to pillage each improvement on affected tiles
  • -50% base yields on affected tiles
  • +2 movement cost on affected tiles
  • -3 visibility on affected tiles
  • 5% chance to destroy vegetation on affected tiles (pillaging improvements)
How it ends
  • Lasts 1 turn

Sandstorm

No duplicates

Full strike

Trigger
  • Can occur from turn 10
  • 5% chance per turn to trigger
  • Strikes a player-owned Arid or Desert tile
  • Spreads across contiguous Dry within 10 tiles
  • Also affects tiles adjacent to the affected area
  • Ignores Water tiles
  • 1-turn warning before it strikes
Tile impact
  • Units on affected tiles take 5 damage/turn
  • -100% base yields on affected tiles
  • +1 movement cost on affected tiles
  • -2 visibility on affected tiles
Terrain changes
  • Arid → Sand (2% chance)
  • Temperate → Arid (2% chance)
  • Lush → Temperate (2% chance)
How it ends
  • Lasts 1 turn

Mitigated

Strikes in place of the full calamity when the calamity is mitigated, and it has no trigger of its own.

Trigger
  • Strikes a player-owned Arid or Desert tile
  • Spreads across contiguous Dry within 5 tiles
  • Ignores Water tiles
Tile impact
  • Units on affected tiles take 3 damage/turn
  • -50% base yields on affected tiles
  • +1 movement cost on affected tiles
  • -2 visibility on affected tiles
Terrain changes
  • Arid → Sand (1% chance)
  • Temperate → Arid (1% chance)
  • Lush → Temperate (1% chance)
How it ends
  • Lasts 1 turn

Tsunami

No duplicates

Full strike

Trigger
  • Can occur from turn 25
  • 5% chance per turn to trigger
  • Strikes a player-owned Coastal Water tile
  • Spreads across contiguous Coast within 10 tiles
  • Also affects tiles adjacent to the affected area
  • Ignores Ocean tiles
  • 1-turn warning before it strikes
Tile impact
  • Units on affected tiles take 8 damage/turn
  • 50% chance to pillage each improvement on affected tiles
Terrain changes
  • Flat → Water (2% chance)
How it ends
  • Lasts 1 turn

Mitigated

Strikes in place of the full calamity when the calamity is mitigated, and it has no trigger of its own.

Trigger
  • Strikes a player-owned Coastal Water tile
  • Spreads across contiguous Coast within 5 tiles
  • Also affects tiles adjacent to the affected area
  • Ignores Ocean tiles
Tile impact
  • Units on affected tiles take 5 damage/turn
  • 20% chance to pillage each improvement on affected tiles
Terrain changes
  • Flat → Water (1% chance)
How it ends
  • Lasts 1 turn

Flood

No duplicates

Full strike

Trigger
  • Can occur from turn 10
  • 5% chance per turn to trigger
  • Strikes a player-owned River tile
  • Spreads along contiguous fresh water and river tiles
  • 1-turn warning before it strikes
Tile impact
  • 20% chance to pillage each improvement on affected tiles
  • -100% base yields on affected tiles
  • Affected tiles are impassable
Terrain changes
  • Flat → Lake (1% chance)
  • Hill → Flat (2% chance)
How it ends
  • Lasts 1–3 turns
  • 50% chance per turn to end

Mitigated

Strikes in place of the full calamity when the calamity is mitigated, and it has no trigger of its own.

Trigger
  • Strikes a player-owned River tile
  • Spreads across contiguous Lake within 5 tiles
  • Spreads along contiguous fresh water and river tiles
Tile impact
  • 10% chance to pillage each improvement on affected tiles
  • -50% base yields on affected tiles
  • Affected tiles are impassable
Terrain changes
  • Hill → Flat (1% chance)
How it ends
  • Lasts 1 turn

Started byAll at Once(as it opens)

Earthquake

No duplicates

Full strike

Trigger
  • Can occur from turn 10
  • 5% chance per turn to trigger
  • Strikes a player-owned Urban tile
  • Spreads across contiguous Non Mountainous Land within 10 tiles
  • 1-turn warning before it strikes
Effects
  • Affected Cities: -2 Stone / Urban
  • Affected Cities: -2 Stone on Urban tiles
Tile impact
  • Units on affected tiles take 4 damage/turn
  • 10% chance to pillage each improvement on affected tiles
Terrain changes
  • Flat → Hill (1% chance)
  • Hill → Flat (1% chance)
How it ends
  • Lasts 1 turn

Mitigated

Strikes in place of the full calamity when the calamity is mitigated, and it has no trigger of its own.

Trigger
  • Strikes a player-owned Urban tile
  • Spreads across contiguous Non Mountainous Land within 5 tiles
Effects
  • Affected Cities: -1 Stone / Urban
  • Affected Cities: -1 Stone on Urban tiles
Tile impact
  • Units on affected tiles take 3 damage/turn
  • 5% chance to pillage each improvement on affected tiles
Terrain changes
  • Flat → Hill (1% chance)
  • Hill → Flat (1% chance)
How it ends
  • Lasts 1 turn

Wildfire

No duplicates

Full strike

Trigger
  • Can occur from turn 10
  • 5% chance per turn to trigger
  • Strikes a player-owned Trees tile
  • Spreads across contiguous Trees within 10 tiles
  • 1-turn warning before it strikes
Tile impact
  • Units on affected tiles take 4 damage/turn
  • Pillages all improvements on affected tiles
  • Affected tiles are impassable
  • 20% chance to destroy vegetation on affected tiles (pillaging improvements)
  • Destruction spreads to adjacent tiles (80% chance, halving each step)
Terrain changes
  • Arid → Temperate (1% chance)
  • Temperate → Lush (1% chance)
How it ends
  • Lasts 1 turn

Mitigated

Strikes in place of the full calamity when the calamity is mitigated, and it has no trigger of its own.

Trigger
  • Strikes a player-owned Trees tile
  • Spreads across contiguous Trees within 5 tiles
  • Ignores Water tiles
Tile impact
  • Units on affected tiles take 2 damage/turn
  • 50% chance to pillage each improvement on affected tiles
  • Affected tiles are impassable
  • 10% chance to destroy vegetation on affected tiles (pillaging improvements)
  • Destruction spreads to adjacent tiles (80% chance, halving each step)
Terrain changes
  • Arid → Temperate (2% chance)
How it ends
  • Lasts 1 turn

Volcanic Eruption

No duplicates

Full strike

Trigger
  • Can occur from turn 10
  • 5% chance per turn to trigger
  • Strikes a player-owned Volcano tile
  • Spreads across contiguous Volcano
  • Also affects tiles adjacent to the affected area
  • 1-turn warning before it strikes
Effects
  • Cities with affected territory: -100% Farm
  • Cities with affected territory: -100% Lumbermill
Tile impact
  • Units on affected tiles take 10 damage/turn
  • Pillages all improvements on affected tiles
  • Affected tiles are impassable
How it ends
  • Lasts 1 turn

Mitigated

Strikes in place of the full calamity when the calamity is mitigated, and it has no trigger of its own.

Trigger
  • Strikes a player-owned Volcano tile
  • Spreads across contiguous Volcano
  • Also affects tiles adjacent to the affected area
Effects
  • Cities with affected territory: -50% Farm
  • Cities with affected territory: -50% Lumbermill
Tile impact
  • Units on affected tiles take 5 damage/turn
  • Pillages all improvements on affected tiles
  • Affected tiles are impassable
How it ends
  • Lasts 1 turn

World transformations Wrath of Gods

Scenarios and map scripts use these slow occurrences, which reshape terrain every turn instead of striking once. The variants differ only in how fast they work.

Ebbing Sea

Each turn, Coastal Water and Lake Tiles have a chance to become Arid terrain. There is also a small chance that newly transformed tiles will have Scrub, Marble, Sorghum, or Salt added to them.

  • Slow: Affects all Shallow Water tiles on the map · Does not end on its own
  • Medium: Affects all Shallow Water tiles on the map · Does not end on its own
  • Fast: Affects all Shallow Water tiles on the map · Does not end on its own
Terrain change SlowMediumFast
Lake → Arid 1%2%3%
Coastal Water → Arid 1%2%3%
Arid → Scrub 10%10%10%
Arid → Marble 1%1%1%
Arid → Salt 0.7%0.7%0.7%
Arid → Sorghum 1%1%1%

Desolation

Each turn, Tiles adjacent to desert become more arid. Deserts will expand to eventually cover the map.

  • Slow: Affects all Sand tiles on the map · Also affects tiles adjacent to the affected area · Does not end on its own
  • Medium: Affects all Sand tiles on the map · Also affects tiles adjacent to the affected area · Does not end on its own
  • Fast: Affects all Sand tiles on the map · Also affects tiles adjacent to the affected area · Does not end on its own
Terrain change SlowMediumFast
Arid → Sand 5%10%20%
Temperate → Arid 5%10%20%
Lush → Temperate 5%10%20%
Marsh → Lush 2.5%5%10%
Lake → Marsh 1%2.5%5%

Tumbling Mountain

Global
  • Short: Spreads across contiguous Sand · 59-turn warning before it strikes · Ends immediately after it strikes
  • Medium: Spreads across contiguous Sand · 79-turn warning before it strikes · Ends immediately after it strikes
  • Long: Spreads across contiguous Sand · 99-turn warning before it strikes · Ends immediately after it strikes
  • Gradual: Spreads across contiguous Sand · 19-turn warning before it strikes · Does not end on its own
Terrain change ShortMediumLongGradual
Mountain → Hill 100%100%100%1%

Rejuvenation

Each turn, terrain becomes more temperate, and resources are slowly added to the map.

  • Affects all Land or Coastal Water tiles on the map
  • Does not end on its own
Terrain change Chance / turn
Sand → Arid 3%
Arid → Temperate 2%
Temperate → Lush 1%
Bare Arid → Scrub 0.2%
Arid → Trees 0.1%
Bare Temperate → Scrub 0.1%
Temperate → Trees 0.2%
Lush → Trees 0.3%
Arid → Marble 0.04%
Arid → Salt 0.02%
Arid → Silver 0.03%
Arid → Sorghum 0.04%
Arid → Goats 0.04%
Arid → Camels 0.04%
Arid → Incense 0.02%
Arid → Olives 0.03%
Temperate → Gems 0.05%
Temperate → Gold 0.05%
Temperate → Horses 0.05%
Temperate → Sheep 0.05%
Temperate → Wheat 0.05%
Temperate → Elephants 0.03%
Temperate → Fur 0.05%
Temperate → Lavender 0.04%
Temperate → Wine 0.05%
Lush → Ore 0.05%
Lush → Cattle 0.05%
Lush → Pigs 0.05%
Lush → Barley 0.05%
Lush → Game 0.05%
Lush → Citrus 0.05%
Lush → Honey 0.05%
Coast → Dyes 0.03%
Coast → Pearls 0.03%
Coast → Fish 0.03%
Coast → Crabs 0.03%

Eras and crises

Story events start these occurrences, and usually end them too.

Era of Peace

Base game
No duplicates
Effects
  • 2 Growth/City
  • 2 Happiness/City
How it ends
  • Chance to end grows by 2% each turn

Started byEra of Peace(as it opens)

Ended byEra's End(as it opens)

Civil War

Behind the Throne
MajorNo duplicates
Effects
  • -1 Vision Range
  • +10% Rebel Chance
Tile impact
  • 5% chance to pillage each improvement on affected tiles
Characters
  • Characters: 5% chance/turn to become Ambushed By Rebels
How it ends
  • Does not end on its own

Started byTreason and, Perhaps, Murder(as it opens) · From Grand Vizier to Uncrowned King(one choice) · King or Tyrant?(one choice) · Schemes Exposed(one choice) · The Claimant Arrives(one choice) · War and Treachery ×2(one choice) · Wits' End(one choice) · [character] Call to Arms(one choice)

Ended byThe Civil War Ends(as it opens) · [character] End(as it opens) · [character] Surrendered(as it opens) · Aid to the Rebels(one choice) · Nothing Left But Rubble(one choice) · The Civil War Continues ×4(one choice)

Era of Decadence

Behind the Throne
MajorNo duplicates
Characters
  • Characters: 2% chance/turn to become Debauched
  • Characters: 3% chance/turn to become Drunk
How it ends
  • Chance to end grows by 2% each turn

Started byEra of Decadence(as it opens)

Era of Reforms

Behind the Throne
No duplicates

Can lead to new laws when the era ends

Effects
  • -20 Opinion Family
  • -1 Orders/City
How it ends
  • Chance to end grows by 3% each turn

Started byReforms Program(one choice)

Ended by[character] Reforms ×6(as it opens)

Era of Corruption

Behind the Throne
No duplicates
Effects
  • -20 Money/Turn
  • +50% Maintenance
Characters
  • Characters: 2% chance/turn to become Corrupt
  • Characters: 1% chance/turn to become Extravagant
How it ends
  • Chance to end grows by 2% each turn

Started byPersonal Enrichment(one choice)

Defense Rallied

Behind the Throne
No duplicates
Effects
  • [On Regular Military Unit Lost] Unit Emergency
How it ends
  • Lasts up to 10 turns

Religious Upheaval

Empires of the Indus
No duplicates
Effects
  • +10% Spread Chance for World Religion
How it ends
  • 10% chance per turn to end, +2% each turn

Started byRitual Steps(one choice)

Pax Kushana

Empires of the Indus
No duplicates
Effects
  • +5% State Religion Spread Chance
  • -2 Training/City
  • 20 Money/City
How it ends
  • Does not end on its own

Started byPax Kushana(one choice)

Ended byThe End of Peace(one choice)

Sections Frequency Calamities Transformations Eras & Crises