Can a trooper cancel its hidden deployment state by declaring Alert skill when a friendly trooper is attacked in its ZoC? If yes, does the troopers camouflage state also get cancelled? https://infinitythewiki.com/Alert -> Automatic no Roll (non-ARO, non-short) Skill https://infinitythewiki.com/Hidden_Deployment_State 2nd cancelation bullet point: The Hidden Deployment State is automatically cancelled whenever the Trooper declares any Short Skill, Entire Order or ARO. The Trooper's Model or Marker will be placed on the game table, in the position you wrote down, facing in the direction of your choice. 4th cancelation bullet point: If the Trooper declares a Skill, ARO or Entire Order other than those listed above, their Hidden Deployment State is also cancelled. In this case, place the Model that represents the Trooper in the position you wrote down, facing in the direction of your choice. https://infinitythewiki.com/Camouflaged_State Camouflage cancelation The Camouflaged Marker declares an Attack, Look Out!, or any Skill that requires a Roll.
Why do you want to perform "Alert" with your HD Trooper? Alert: At the end of the Order, during its Conclusion, and after performing any Saving Rolls, Troopers that meet the Requirements may turn on the spot, without changing position, to modify their LoF angle as their player chooses. https://infinitythewiki.com/Hidden_Deployment_State 2nd cancelation bullet point: The Hidden Deployment State is automatically cancelled whenever the Trooper declares any Short Skill, Entire Order or ARO. The Trooper's Model or Marker will be placed on the game table, in the position you wrote down, facing in the direction of your choice. As HD and Markers offer 360 degree LoS anyway, I find it hard to think of needing Alert for HD or Marker Troopers.
Better Order generation next turn and preventing cautious moves on the enemy turn. Basically the same thing that you can(?) do with Look Out! but with different triggering mechanism and keeping the all important camoflaged state.
I think you want cancellation clause three as it appears that Alert is not on the list of things that cancel Hidden Deployment and allow Camouflage to be retained.
This has come up under a couple different routes, most notably for people wanting to pull a hidden lieutenant out of HD right before their first turn. As of the current FAQs reworking the order sequence and ZoC measurements, it’s mostly not really possible anymore. Since this is just a change of facing and hidden models don’t have facing, I don’t think it really works. You can declare a ZoC ARO if an enemy gets close enough, but that will fully reveal your model. Might still be worth it if you want to get tactical awareness orders and similar for it.