Grey Talon takes damage from Storm Cloud even while behind walls, if his Guided Owl is both in line of sight and within range of the ultimate.
This works the opposite way as well, if Talon is both in line of sight and within range, he does not take damage as long as his Guided owl is either out of line of sight or out of range of the ultimate.
This probably works similarly with Lash's ult or other abilities which rely on a line of sight mechanic.
I believe the "line of sight check" is linked to the owl and the "range check" is linked to the character itself.
This works the opposite way as well, if Talon is both in line of sight and within range, he does not take damage as long as his Guided owl is either out of line of sight or out of range of the ultimate.
This probably works similarly with Lash's ult or other abilities which rely on a line of sight mechanic.
I believe the "line of sight check" is linked to the owl and the "range check" is linked to the character itself.