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🌋 Occurrences

35 occurrences16 calamities11 transformations8 eras & crises

Occurrences are persistent world events that stay on the map for several turns. The headline set — the Calamities — ships with the Wrath of Gods DLC and strikes on its own clock; the era and crisis occurrences below are started by events. Every number here is read straight from occurrence.xml.

Calamity Frequency Wrath of Gods

Chosen 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 if it can't 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)
  • Arid → Sand (1% chance)
  • Temperate → Arid (1% chance)
  • Lush → Temperate (1% chance)
How it ends
  • Lasts 3–5 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, +5% each turn
  • When it ends: Infected characters recover
  • When it ends: Incubated characters recover
  • Won't repeat while the Plague memory lingers

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 it is mitigated — no independent trigger.

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 it is mitigated — no independent trigger.

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 it is mitigated — no independent trigger.

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 it is mitigated — no independent trigger.

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

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 it is mitigated — no independent trigger.

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 it is mitigated — no independent trigger.

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 it is mitigated — no independent trigger.

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

Slow-burn occurrences used by scenarios and map scripts — they reshape terrain every turn rather than striking once. Variants differ only in pace.

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 & Crises

Event-driven occurrences — started and usually ended by story events rather than the calamity clock.

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

Civil War

Behind the Throne
MajorNo duplicates
Effects
  • -1 Vision Range
  • +10% Rebel Chance
  • -1 Vision for all Units
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

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

Era of Reforms

Behind the Throne
No duplicates

Can lead to new laws when the era ends

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

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

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
  • +10% World Religion Spread Chance
How it ends
  • 10% chance per turn to end, +2% each turn

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
Sections Frequency Calamities Transformations Eras & Crises