Field Device LUD-99X
- This article is about the operation mechanic. For the Collectible, see Field Device LUD-99X (Collectible).
The Field Device LUD-99X is an operation mechanic[note 1] in the Integrated Strategies game mode of Arknights, featured in Expeditioner's Joklumarkar where it is present in operations throughout Deep Investigation (introduced in Expansion I) so long as the player has the 
Field Device LUD-99X.
Overview
Like that of the Londinium Secondary Defense Artillery, the Field Device LUD-99X causes the friendly unit with the highest block count[note 2] (if there are multiple, the Field Device will target the most recently deployed one) to be highlighted by a red crosshair with the 3×3 tiles area with 3-tile extensions to the four cardinal directions centered on them also highlighted with orange borders.
What separates the Field Device LUD-99X from the Artillery is that it will linger for 5 minutes after the operation starts and applies one of the following effects within the radius every 10 seconds, chosen at random:
- All units are Stunned for 10 seconds and the player gains 15 Recon Proficiency
- A random unit is Frozen for 20 seconds and the player gains 20 Recon Proficiency
- A random friendly unit loses 30 SP and the player gains 20 Recon Proficiency
- A random friendly unit restores 10 SP (can target those who cannot restore/recover SP such as Duelist Defenders without an Operator Module, but will be wasted) and the player gains 10 Recon Proficiency
- A random unit takes 1500 True damage and the player gains 15 Recon Proficiency
- A random unit restores 1000 HP (can target those who cannot be actively healed such as Musha Guards, but will be wasted) and the player gains 10 Recon Proficiency
Notes
- ↑ Technically provided by a static device of the same name, which is hidden in-game.
- ↑ Friendly units with an aggression level of 1 or higher are considered by the Field Device LUD-99X to have that increased amount of block count.