Festering Skies
Warning! Spoilers ahead!
work in progress
Contents
Initiating the DLC and starting conditions
To play the DLC you need to purchase and install Festering Skies (which is not part of the Year One Edition released in December 2020), start a new game and make sure that Festering Skies is selected.
It is highly recommended that, at least the first time, you play Festering Skies with the hints and tips on (you can do this in the gameplay options), as these panels are used both to explain essential mechanics and for storytelling purposes.
Special starting conditions:
- There is a number of
bases with a free 
Manticore (depending on difficulty level: 3 on Rookie, 2 on Veteran, 1 on Hero and 0 on Legend). They will have the Manticore icon next to them on the Geoscape. Remember that you have to research The Phoenix Archives to see the bases on the Geoscape. - There are less haven defense missions.
The DLC starts on January 3rd, with an ominous message from 
Disciples of Anu. Shortly after, the Egg arrives with a cutscene. Mount Egg will then appear somewhere near your starting base. You cannot interact with Mount Egg in any way.
On January 9th you will receive a message from 
Synedrion and a mission (the Gift), which you will have 15 days to complete.
The Gift
This mission will be generated at the haven nearest to your starting base.
Beware that choosing 'START' will commence the mission immediately, without giving you the chance to equip your troops with the usual deployment screen
The mission requires you to reach an evac zone at the other end of the map to escape a haven under Pandoran attack in a fully armed . There are a lot of enemy reinforcements on this map, and lot of enemies towards the end of the mission. Don't try to kill them all: the objective is to escape. As all missions of similar type, it's easier with a vehicle.
You can also easily complete the mission with a single 
Heavy using 
Also, as you get the fully armed even if you fail, you can sacrifice a single unarmed LVL1 operative
Some things to note:
- The aircraft you arrive in is destroyed. If you have the hints active, this will be told in a tutorial panel (it will say "our transport was lost in the sinkhole").
- If you arrive on two or more aircrafts, the last one to arrive and start the mission will be destroyed.
Once you complete the mission, you will be introduced to the aerial combat minigame with a tutorial.
After your complete minigame tutorial your new (named 'The Gift') will be automatically teleported to the nearest base. Also, Citizen Eillen (a 
Sniper) will join your ranks and if there are no available seats on the aircraft, one of your operatives will be assigned to the same base.
Aerial minigame
The minigame is fairly simple. All human aircraft have slots for 2 weapons and 1 special module, usually a counter to specific type of attack that allows you to ignore it (for example, the starting special module is afterburner, which, while active, makes all visually guided attacks miss the craft).
You only have control over what weapons to use and on what (whether on the hull of the enemy craft or on a weapon/module), when to activate the special module (though some are passive and always on), and whether to disengage. This last part is very important: you can press the disengage button at any time to leave the combat in 5 seconds. This can be abused to damage an enemy aircraft using long range weapons, leave the combat before the enemy can respond, and attack again, and so on and so forth.
If your craft is destroyed, the operatives on it will take 100 HP damage each and be automatically teleported to a base.
The Behemoth
After completing the Gift and the aerial combat tutorial, you will see the Behemoth where Mount Egg used to be.
The Behemoth cannot be engaged directly. It roams the land until its 'Disruption meter' is filled up, and then it submerges, to reappear somewhere else some time later (about one week?). While it is roaming the land, it destroys havens, infests them, or damages the districts (on lower difficulties it's more likely that the Behemoth will damage districts, rather than destroy the haven outright). It also launches Pandoran flyers (of which there are 3 different types) and which will attempt different missions (recon, supply, raid or infestation) on havens and bases (and sometimes other Points of Interest (POI), for no apparent reason - possibly a bug)
Engaging other aircraft and Pandoran flyers
To engage (initiate the aerial combat minigame) one of your aircraft must be at the same POI and you have to choose the intercept option in the location actions menu.
Note that you cannot engage or otherwise interact with an aircraft or a Pandoran flyer that's not at a POI.
Destroying Pandoran flyers yields resources in the form of 
or 
, positive attitude adjustment with factions and (sometimes) aerial weapons or modules.
Pandoran flyers missions
Recon
Открывает базы феникса для Бегемота
Supply
The flyer will harvest resources from the haven.
Raid
The flyer will damage districts at the haven.
Infestation
The flyer will infest the haven.
Infested havens
Once the Pandorans evolve Berith (a type of flyer) and Corruption Node, havens may become infested by the Behemoth instead of destroyed or damaged, or by a Berith with an infestation mission.
If a haven is infested, the faction aircraft in it will be taken over by Pandorans, and may be engaged in the aerial minigame and may carry out raid missions on other havens.
To liberate the haven you will have to complete a new tactical mission.
How to destroy the Behemoth
You have to
- complete the Virophage weapons research
- carry out autopsy of Corruption Node
- research and build a 'Masked Manticore' (requires completing both previous steps and
) - assault the Behemoth (once the Masked Manticore is selected on the Geoscape, there is a button to the left of the roster that when clicked allows to initiate the mission)
can be acquired by destroying Pandoran flyers or infected aircraft over Disciples of Anu havens, from captured Pandorans, and in lairs or citadels
Assault on Behemoth mission
Q: How to deal with the Behemoth?
A: The Behemoth is not able to be attacked head-on, and you cannot intercept the Behemoth itself. It will head towards havens and send flying Pandorans on missions across the Geoscape. By successfully intercepting flyers, you earn disruption points towards countering the Behemoth. At the top of the Geoscape, there is a Behemoth window, where you can see how many disruption points need to be achieved. Once this threshold is met, the Behemoth will retreat and submerge into the ocean for a while. However, after some time, it will return. To defeat the Behemoth once and for all, you’ll need to research a means at stopping it.
Q: How to play the Interception air combat minigame?
A: Interception is a fairly straightforward minigame, where two aircrafts face off 1v1 until one aircraft’s hull is destroyed or the player disengages. All human aircrafts have slots for 2 weapons and 1 special module, usually a counter to a specific type of attack (for example, the starting Phoenix Project special module is afterburner, which, while active, makes all visually guided attacks miss the craft).
The minigame starts with the two aircrafts at opposing ends, slowly coming towards one another. You will see weapon ranges displayed for both your equipped weapons and the enemy’s. As either aircraft enters range, weapons will automatically fire against the selected target, and then enter a cooldown state before firing again.
Players have control over which weapons to use and to aim them at the enemy hull or enemy weapon/modules. Different weapons have different guidance systems to counter, which you will research and manufacture throughout the DLC. Certain modules can be activated to evade enemy missiles, etc.
At any point, players can choose to disengage and run from the fight. There’s no shame in fleeing, but note that it takes 5 seconds and you can be destroyed before disengaging. If your aircraft is destroyed, any operatives onboard will be hurt for around 100 HP damage and be transported to a Phoenix base.
Q: How do I destroy the Behemoth for good?
A: To start the process of stopping the Behemoth, you will need to have won at least one Infested Haven mission by destroying the Corruption Node. Destroying the Corruption Node unlocks the Corruption node autopsy research, which is required alongside Virophage Weapons to open the path to researching a Masked Manticore. Be warned: Masked Manticores are seen as hostile entities to factions, even if not at war with that faction.
Once you have a Masked Manticore, you can land on the Behemoth to begin the final mission and potentially end its reign of terror.
