From MechWarrior: Living Legends Wiki
The default Crouch/Deploy key is the Left [ctrl] key.
Crouching and Deploying are beneficial in someways and detrimental in others.
- Mechs can pitch their torso higher up while crouched in order to shoot at Aerospace, VTOLs, or other targets at a much higher elevation.
- Mechs have a shorter profile when crouched, making it easier to hide behind shorter objects.
- Long Tom artillery can only be fired while deployed.
- All assets that are deployed or crouched will lock on more quickly with any of their missiles that lock on.
- Tanks, hovercraft, and artillery become more stable while deployed. The player doesn't have to worry as much about sliding down hills when letting off the break or from recoil.
- Players often have difficulty selling their Hovercraft, because they drift all over the build bay. Since powering down engages the repair function, deploying can be a better option when trying to sell a hovercraft.
- The asset cannot move.
- Deploying and Crouching take time to engage and time to disengage, leaving the player vulnerable for longer.