Call of Duty: Ghosts
The Strobe Light only appears once, in the campaign mission "Federation Day". It is used by Logan and Keegan to produce repetitive flashes of light from their weapons in dark areas to disorientate the Federation soldiers, and take them out while they are in this state.
Call of Duty: Black Ops 4
In Black Ops 4, the Strobe Light is featured as an operator mod for the SG12 shotgun. It changes the traditional aiming system for a focus aim with the Strobe Light pulsating causing a temporary blinding light on the screen on affected players. Players who are affected by the Strobe Light will also have their aim assist disabled on the console version of the game, however, Tactical Mask will prevent aim assist from being disabled as of Patch 1.18.
Within Zombies, the effect is changed to a chance of stunning zombies with an effect similar to the Re-Pack perk Kill-o-Watt. The aim system also is not affected by the decreased hipfire gained from Deadshot Dealer.