One of my players wanted to cast an Elemental Wall (Earth) in the shape of a dome (as per the rules for the spell) directly over a hovering target (specifically a Northrup Wasp).
I couldn't find any rules about what constitutes a valid target for a wall spell aside from Line of Sight, which he had, so I allowed it.
Since then I've opted to house-rule that spells that generate a wall (Mana Barrier, Elemental Wall, Physical Barrier) require one side/edge to be in contact with a rigid object that will hold it, at least until another force besides gravity acts on it (the Earth, a building, a parked car). Is there any errata I'm missing about walls or a more common house rule to cover these situations, or is this a completely standard use of the spell?
Edit: A private message enlightened me that "There's nothing in the books that would prevent your player from doing what he did."
Area spells can be cast on a specific target or a point in space that you can see.
- SR5 Core Rulebook, p. 281