After getting Kalakoth's Freezing Rake as a Trickster Rogue, the ability appears to be usable anywhere on a map.
The normal iconography would imply not - you get the usual range circle, but if you actually click anywhere (whether it's a "can't see" icon or just "too far" icon), the spell just casts and affects the given area.
This is Mac GoG version 4.0.1.0041 - game was started back in 3.x days, but I don't know whether it was a problem then or not as I discovered this purely by accident.
The save file is 6M so can't upload it here; I can link to it from external if you actually need it. I've attached an image showing the rake activating in the sky over Periki's Overlook, being cast from outside the Adra Bath House.
This does not affect any of the other ranged trickster abilities (e.g. "Gaze of Adragon" or "Wall of Many Colours")