If you just got the “Ancient Rivals” event in your Stellaris game, a second fallen empire has woken up to face the first one, and the War in Heaven is probably only a couple of years away.

The War in Heaven is a total war between the two awakened empires over who gets to rule the galaxy. Every other empire will have to join one of them as a subject, stay out of it or join the League of Non-Aligned Powers that forms against both. For most empires, the right call is to not join a side at all. Stay neutral, and only lead or join the League if you are strong enough to take on two awakened empires.

All chances, timers and fleet multipliers below were taken straight from the event and script files of Stellaris 4.5.2.

How the War in Heaven Starts

The War in Heaven is a chain of four steps, and it needs the Leviathans Story Pack. Without it, a fallen empire can still wake up, but there will be no War in Heaven.

The First Awakening

Everything starts with the “Sleepers Awake” event, when the first fallen empire wakes up. For a normal awakening, all of these have to be true:

• The game has reached the end-game start year. By default that is 200 years after the start, so 2400 in a game that starts in 2200, and you can set it anywhere between 50 and 800 years in the galaxy settings.
• The fallen empire is not a machine empire, is not at war and has more than 60k fleet power.
• No other fallen empire has awakened before (an Ancient Caretakers awakening does not count).
• At least one regular empire has more than 70k fleet power, or its federation has more than 90k, or it owns a fallen empire world.

Even then, it will not happen at once. The awakening has a mean time to happen of 50 years for each fallen empire, which drops to 25 years if any empire has more than 120k fleet power and to 5 years if a regular empire holds a world taken from one of the other fallen empires. More fallen empires slow it down instead, to 75 years with 2, 100 years with 3 and 125 years with 4 or more. These factors multiply with each other.

Ancient Rival Roll

Right when the first fallen empire wakes up, the game rolls once for an ancient rival. If no rival is picked, that awakening stays a regular awakened empire with no War in Heaven. Only a later Holy Guardians awakening from a ruined holy world rolls again.

Rival Awakening

The ancient rival usually wakes within a few years (mean time 5 years, almost at once after 10 years), but only while it is at peace and has more than 60k fleet power and the first awakened empire is still around, and every empire in the galaxy will then get the “Ancient Rivals” event.

The rival gets the “Revanchist Fervor” and “Ancient Caches of Technology” civics (the BioGenesis hive gets its own), full resource stores (50,000 minerals, 50,000 energy and 40,000 alloys among them) and a fleet scaled to the strongest empire in the galaxy. For the next 10 years, AI empires will not start any new wars.

Start of the War

The war breaks out a couple of years after the ancient rival wakes up. The game waits at least 2 years, and after that the event has a mean time to happen of 1 year, which gets a lot shorter once 10 years have passed since the rival woke up. Both awakened empires need to be at peace with everyone and have more than 60k fleet power for it to fire.

Once it does, the second awakened empire declares a total war on the first one in which neither side can surrender, and every regular empire will get “The War in Heaven” event to pick a side.

Is It an End-Game Crisis?

The War in Heaven is an end-game event, since a normal first awakening waits for the end-game start year. That being said, the game does not count it as a crisis. A crisis can still spawn while the two awakened empires are fighting, so you might have to deal with both at the same time. While the war is running, nobody can win the game when the victory year comes around either.

War in Heaven Chance

The rival roll only looks at which fallen empires exist. If the fallen empire with the opposite ethic is still around (Holy Guardians and Keepers of Knowledge, or Militant Isolationists and Enigmatic Observers), the chance is 60%. With any other mix it is 20%, and with only one fallen empire, not counting the Ancient Caretakers, there is no War in Heaven at all.

The 60% is made up of two parts. There is a 40% chance that the game picks the opposite fallen empire and a 20% chance that it picks a random one, which can also be the opposite. If there is no opposite fallen empire, the 40% part does nothing, and you are left with 20%. So an opposite pair makes a rival three times as likely, but any other pair can still roll one.

The Ancient Caretakers never take part, while the hive fallen empire from BioGenesis can.

Galaxy size does not appear in the event itself. Bigger galaxies only help because they can hold more fallen empires, which makes it more likely that an opposite pair exists. Bear in mind that this chance only covers the rival roll. The first awakening has to happen and both awakened empires still have to reach the war, so there is no fixed percentage for how many of your games will get one.

How to Trigger It

If you want a War in Heaven, you will need the Leviathans Story Pack and at least two fallen empires apart from the Ancient Caretakers, and an opposite pair will give you the best odds.

A natural awakening only happens after the end-game start year you set in the galaxy settings, which is 2400 by default, so an earlier setting lets the fallen empires wake up earlier. Once that year has passed, owning a world taken from one fallen empire makes the other fallen empires wake up ten times faster.

The exception is the Holy Guardians. If an empire they are not at war with destroys or ruins one of their holy worlds (for example by cracking, shielding, deluging, toxifying it or turning it into a tomb world), they wake up within days, whatever the year, and the game still rolls for an ancient rival. The rival’s own awakening has no year check, so the whole chain can start before the end-game year this way.

Finally, leave both fallen empires of your pair alive and keep the peace with them. The War in Heaven only starts while both awakened empires are at peace with everyone and each has more than 60k fleet power. If one of them is busy with another war, the event simply waits. The rival’s awakening has the same peace check, so a war with the rival fallen empire before it wakes will delay it too.

How to Avoid It

There is no setting that turns off only the War in Heaven. Fewer fallen empires in the galaxy settings, or killing fallen empires before the end-game year, are the only ways to avoid it or make it rarer. With no fallen empires, or only one apart from the Ancient Caretakers, the chance is 0%, and without the Leviathans Story Pack you will not get one either.

In a running game, you are going to have to take fallen empires out before the end-game year, since a natural awakening waits for it. Killing one of each opposite pair brings the chance down to 20%, and a single fallen empire left standing, apart from the Ancient Caretakers, brings it to 0%. Our fallen empire guide has more on how to fight one.

Leave the holy worlds of the Holy Guardians alone while you do this, since ruining one wakes them up at once. Additionally, once any regular empire holds a conquered fallen empire world, the remaining ones will wake up much faster after the end-game year.

If you want to keep the War in Heaven but make it hurt a little bit less, use the Fallen Empire Strength slider in the galaxy setup. It goes from 0.25x to 5.0x and controls the fleet strength of fallen and awakened empires. At 0.25x, even a Grand Admiral awakened empire will only aim for half the fleet power of the strongest empire.

Which Side Should You Pick?

When the war breaks out, you will get “The War in Heaven” event with four buttons:

• “We will stand with [first awakened empire].” joins the empire that woke up first.
• “The [second awakened empire] have our allegiance.” joins its rival.
• “We will not take sides in this conflict.” keeps you neutral.
• “They will both fall to our might!” sounds like a challenge to both of them.

The fourth button is pure flavour. It has no effect of its own and works exactly like staying neutral. Subjects only get “As a subject nation, it is not up to us to decide.” and follow their overlord into the war if it is one of the awakened empires. Joining a side also needs you to not already be at war with an awakened empire and not be a declared crisis.

Subject Types

If you join one of them, you become a subject of that awakened empire and enter its war. You also get +100 opinion with your new overlord and -100 with the other one. Both fade by 2 per month. Your subject type depends on who you join:

The Holy Guardians are the only ones who touch your ethics. Unless you are a gestalt consciousness, joining them will shift your empire towards Fanatic Spiritualist.

AI empires make this choice by weight. An AI empire that borders one of the awakened empires will usually join it, while strong AI empires usually stay neutral, and AI empires in a federation are more likely to.

I would say joining a side is rarely worth it. As a Thrall, Dominion or Satellite, you will pay a 30% tithe on your basic resources or research, and you are going to be stuck in a total war in which surrender is not an option. Neutral is the default choice for almost every empire. If you are strong, it also keeps the League open to you.

Staying Neutral

Picking neutral does not put you in the League. You get an invitation and can say no, and then you are not part of the war at all, at least until someone declares on you. Make sure to answer the side-choice event yourself.

Many players sit out the whole War in Heaven this way and report that the awakened empires mostly leave them alone, as long as they are strong enough or live far away from both. A weak empire right next to one of them is likely to have a much harder time.

The war will end at some point, though. If one awakened empire beats the other, it fully annexes the loser and comes out of the war a lot bigger than before. The years of the war are probably the best time to build up your economy and your fleet.

Genocidal empires such as Fanatic Purifiers, Devouring Swarm and Determined Exterminators are a different story. They are never asked to lead or join the League, and players report that the awakened empires usually end up at war with them sooner or later.

The League of Non-Aligned Powers

The League of Non-Aligned Powers is the federation of empires that stay out of both sides and fight the awakened empires together. The game picks its leader in this order:

Subjects, anyone at war with an awakened empire (so everyone who joined a side), genocidal empires, player crises at level 4 or 5 and anyone who declined before are skipped. The League also only forms if there is no Galactic Emperor. If you want to lead it, be the Galactic Custodian or lead the strongest federation.

The empire that gets asked can accept with “We will lead this league!” or decline, and then the next candidate is asked.

Members and Federation

An existing federation simply becomes the League under the new name. If the leader had none, a new federation is formed as soon as the first member joins, and it starts out with enough federation experience for level 3 as well as +100 cohesion. If you accept the leadership while you are a member of someone else’s federation, you will leave it.

Independent, non-genocidal AI empires that are not at war with an awakened empire ask to join during the first 180 days after the leader accepts. As the leader, you can accept or refuse them, but a refused empire takes -100 opinion of you, which fades by 1 per month. Everyone who joins leaves their other wars and federations, and AI members cannot leave the League for 20 years.

League members get +200 opinion of each other, while the League and the awakened empires get -200 opinion of each other. Both fade by 2 per month.

Six to nine months after the League forms (a 180-day window, then a mean time of 3 months), both awakened empires declare war on it with the “War with the Awakened” event, and their subjects join in. This war uses the same war goal as the War in Heaven, so the League can only end it with a total victory or a status quo.

Galactic Imperium

If someone has already proclaimed the Galactic Imperium, there is no League. Every member of the Galactic Community leaves its current wars, both awakened empires declare the War in Heaven on the Galactic Emperor, and every other member joins on the Emperor’s side. The Emperor also gets +100 Imperial Authority, while empires outside the Galactic Community get the normal side-choice event.

How to Win the War in Heaven

As the League, you have to finish off both awakened empires in the end. You can destroy one while the two are still fighting each other, or let them wear each other down and finish off the survivor, but killing the first one does not end the survivor’s war with the League.

Awakened Fleet Size

Since patch 4.4, an awakened empire spawns fleets until it matches the fleet power of the strongest empire in the galaxy, multiplied by a factor for difficulty and the Fallen Empire Strength slider. At the default 1x slider, that is half of it on Civilian, the same on Ensign and twice as much on Grand Admiral. This happens once, when it wakes up, with one fleet first and up to 10 more after that.

For reference, this is the target against an empire with 100k fleet power at the 1x slider:

The slider multiplies this further. On Grand Admiral, a 0.25x slider brings the multiplier down to x0.5, while 2x raises it to x4.0 and 5x takes it all the way to x10.0.

Because the target is the fleet power of the strongest empire at the moment of awakening, a big fleet built up right before they wake up will also raise the size of what they spawn, if it makes you the strongest empire.

Decadence

Awakened empires start to decay 20 years after they wake up, and the bigger they and their subjects grow, the faster their Decadence grows from month to month. At its worst, Decadence cuts their job output by 66% and their ship damage, hull, armor and shields by 25% each. As such, waiting it out is a real option, especially against an awakened empire that has grabbed a lot of planets. It rises in random steps, though, so you cannot plan around a fixed year.

Galactic Community Resolutions

While the war runs and there is no Galactic Emperor, the Galactic Community can pass one of three focus resolutions, and passing one repeals the other focus resolutions. “Focus: Denounce [first awakened empire]” and “Focus: Denounce [second awakened empire]” make it a Breach of Galactic Law to not join the side that was not denounced.

“Focus: Denounce Both Awakened Empires” makes joining either of them a breach instead, and every Galactic Community member that is not a subject of either awakened empire gets +25% damage against awakened empires while the war lasts. If you lead the League, that is the one to push for.

Fleets and Tactics

What works for most players against awakened empires in 4.x is to skip strike craft and missiles, hold chokepoints with starbases and fleets, split their own fleets into several groups and hit the awakened empire’s planets while its doomstack is busy somewhere else. For the ship designs, have a look at our fleet composition guide, and at the titan build guide if you want a titan leading the fleet.

How the War Ends

If one awakened empire beats the other, the winner fully annexes the loser and you will get “The End of the War in Heaven”.

The two awakened empires can also end their war in a status quo, and then the galaxy is left with both of them, each pulling its fleets back to its own borders. Many players report that the game still counts the War in Heaven as running after that, which blocks a victory and the Galactic Imperium until an awakened empire is destroyed.

If the League destroys one awakened empire while the two are still fighting each other, you get “Awakened Empire Defeated” and the fight between the two awakened empires is over. The survivor’s own war with the League goes on, though, and the War in Heaven only ends once the League destroys that one too.

If the last awakened empire of the war is destroyed after the other one is already gone, and the war has not already ended with “The End of the War in Heaven”, you get “The Fall of the Awakened”. The League also gets “War in Heaven is Over” for good, which gives it -5 federation cohesion per month.

As long as the war is running, the game will tell you “It is not possible to win during the War in Heaven”, and the Galactic Imperium cannot be proclaimed either. Its resolution is blocked with “Conditions are too chaotic to proclaim the Galactic Imperium during the War in Heaven.”

Last, Best Hope Achievement

The “Last, Best Hope” achievement needs the Leviathans Story Pack. It goes to the leader of the League of Non-Aligned Powers when the last awakened empire of the war is destroyed while the War in Heaven still counts as running. In practice, wait for the awakened empires to declare war on the League, then destroy both of them yourself, in either order. If one awakened empire wins outright and you get “The End of the War in Heaven”, the war counts as over and finishing the winner no longer gives the achievement.

Under a Galactic Emperor there is no League, so you cannot get it on the Galactic Imperium path. If you are going for it, let the awakened empires declare war on the League instead of attacking them first.

Conclusion

For most empires, the War in Heaven is something to sit out. Pick the neutral button, turn down the League if you are not strong, and let the two awakened empires grind each other down while you build up.

If you are the Galactic Custodian or lead the strongest federation, I would say leading the League is a fair choice. If you are after “Last, Best Hope”, wait for the awakened empires to declare war on the League and destroy both of them yourself. If you would rather not see the War in Heaven at all, take out all but one of the fallen empires before the end-game year, not counting the Ancient Caretakers, or start with fewer of them.