Londinium Secondary Defense Artillery

“	Once fully charged, deals area True damage to both allies and enemies, centered on the friendly unit with the highest Block.	”
	—Description of operations with the Londinium Secondary Defense Artillery

The Londinium Secondary Defense Artillery is an operation mechanic in Arknights, introduced in Episode 10.

Some of Londinium's gun batteries

The Londinium Secondary Defense Artillery is based on an artillery gun battery in the fortified walls of Londinium that were originally intended to protect the city from outside threats. Following the occupation of Londinium by the Military Commission of Kazdel, however, the battery is repurposed to demolish inside threats standing against their construction of The Shard. Since it was meant to fire at targets outside Londinium, the gun was inaccurate against targets inside, but the collaborating Victorian gunnery under Lettou's leadership managed to rectify this problem by using automatic tracking computers. The gun battery is eventually destroyed by Rhodes Island during their escape from the now-compromised Eartha hideout in Sudean Borough.

Overview

The Londinium Secondary Defense Artillery meter, close to full

Gravel is being targeted by the Londinium Secondary Defense Artillery

The Londinium Secondary Defense Artillery in action

A meter will be shown on the HUD, below the enemy count and Life Point indicator, if the Londinium Secondary Defense Artillery is present in the operation, which slowly fills itself at a rate of 1 every second; the meter has a cap of 120. Yellow exclamation marks will be shown on the meter's sides once it is over 50%, then a reddish smoke will be shown at the edges of the screen once the meter is over 90%. During this time, the Artillery will target the friendly unit with the highest block count who is not invisible/camouflaged (if there are multiple, the Artillery will target the most recently deployed one), highlighted by a red crosshair with the area of 3×3 tiles with 3-tile extensions to all four cardinal directions centered on them also highlighted with orange borders, showing the Artillery's area-of-effect.

Once the Londinium Secondary Defense Artillery meter is full, the exclamation marks will turn red; if there is at least one valid target on the map, the Artillery will fire, dealing 3000 True damage to the target and all other units, both friendly and enemy, within the Artillery's AoE, and can even damage invisible units, after which the meter resets to 0. Despite all the danger the Londinium Secondary Defense Artillery poses to operators, its use is necessary to effectively deal with Reborn Creations since they will only take a measly 10% Physical and Arts damage, leaving True damage sources (including the Artillery) the most effective way to deal with them.

Watch out for the following enemies, who can rapidly fill the Londinium Secondary Defense Artillery meter:

Enemy	Method	Value
	Special ability (lasts 20 seconds, once per operation, used in 5 seconds after spawning)	1 per second
	Attack	1
	Teekazwurtzen attack	1st phase: 3 2nd phase: 6

Interactions

Enemy	Interaction
	If the Artificer is disabled or defeated while using their special ability, the Londinium Secondary Defense Artillery meter will be reduced by 15 (cannot be reduced below 0).
	If Manfred is struck by the Londinium Secondary Defense Artillery, he will be Stunned for 8 seconds and his Military Training will be disabled for 30 seconds.

Appearances

Main Theme	10-4 • 10-6 • 10-7 • 10-8 • 10-11 • 10-12 • 10-14 • 10-15 • 10-16 • 10-17 • 13-2 • 13-4 • 13-5 • H10-1 • H10-2 • H10-3 • TR-20
Story Collections	AW-1 (Challenge Mode)
Contingency Contract	Londinium Outskirts
Trials for Navigator	Fissure Strike
Paradox Simulation	Humus: "Stern as Steel"

Trivia

• In the Story Environment mode, the ATK buff applies to the Londinium Secondary Defense Artillery, increasing the damage dealt to 6000 which is able to defeat most normal enemies in one salvo.