Infiltrators skills
It seems the infiltrator arrow will work only if the game finds waypoints that would allow you to get where you aim by walking, and if it is not a too long / too complex path.
Pretty much the kind of system that allows NPCs to move from point A to point B, where if you need to make them jump you need to add a script during the pathing, by comparison.
Also, there are many situations where you can shoot under a surface to get teleported on top of it, still this surface has to be reachable by foot.
There are some exceptions which seem to contradict my beliefs, like how you can shadowstep to the pontoon bridge of the ship during Raid on the Capricorn (although i still suspect the game manages to calculate a path through water)
Anyway, most of the time, if you’re trying to cross a gap that can only be reached by jumping, infiltrator’s arrow won’t work.
Simple explaination to the numerous instant movements:
A shadowstep skill(pretty much 99% of the thief gap closers) will only work if you could WALK the same path in a STRAIGHT line.
A teleportation skill(the downed skill seems to work like that) will only work, if there is a PATH leading to your destination. Don’t know how far the path finding goes but as a rule of thunb, if there is any way to reach your destination without jumping, a teleport will take you there.
Lastly, Portal will take you anywhere from everywhere.
The mob has spoken and the turrets shall be burnt at the stake.