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
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    \$\begingroup\$ This could almost be a system-agnostic question, what with Stoneshape, Wall of Iron, and other such spells having varying amounts of vagueness in a lot of games. \$\endgroup\$
    – mech
    Mar 7, 2016 at 19:56

1 Answer 1


While I cannot answer to there being any errata or rules that you're missing (I couldn't find any on a quick look), we do have a houserule in most games I'm involved with when it comes to wall/structure generation spells:

Unless intended (read: balanced) to be destructive in nature, you are required to cast wall/structure spells (Wall of Earth, Summon Wood Cabin, ...) so that they sit on stable surfaces that the caster reasonably believes can hold their weight at the conclusion of the casting, without taking into account outside influences (weather, subsequent spells, previous spell effects ending).


  • Creating a Wood Cabin at the edge of a cliff, with small parts of the structure having no support is fine.
  • Creating a Wood Cabin in a dry river bed, knowing that the bed will flood in the next round/hour/day and destroy the cabin, is fine.
  • Creating a Wall of Fire on a pit of quicksand is fine, since the Wall of Fire has no weight.
  • Creating Wall of Iron on the flat roof of a rickety straw hut is not OK, as it's very likely to collapse.

This, of course, can be somewhat worked around by the players with the use of clever planning (summoning a temporary structure, placing the desired creation above or within it, and then dispelling the temporary structure), but players should be rewarded for clever planning, and it should still stop them from using utility spells for impromptu destructive needs.

  • \$\begingroup\$ That would obviously render the helicopter an invalid target, but it sounds a bit like cartoon physics? "I don't know it will fall, so I can attempt it." If a Wall of Fire has no weight then it could conceivably be supported by the wind. Would your rule make that an invalid target? Would it hover or float away on the breeze? \$\endgroup\$
    – Gavin42
    Mar 7, 2016 at 20:51
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    \$\begingroup\$ Wind/air is not a surface by any reasonable interpretation (at least not in my weekly games ;-P), and the rule says that wall spells require surfaces. Think of it cinematically: as you cast the spell, you are shaping a carefully-thought-out construct--if it shifts too much as you're building upon it, the entire thing crumbles (i.e. the spell fizzles). Regarding breezes, that would depend on the specific spell. Most incarnations of Wall of Fire create a wall that is "affixed" to the surface it's cast to (so if you were to set it on a movable surface such as an airplane's wing, why not?). \$\endgroup\$
    – mech
    Mar 7, 2016 at 20:58
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    \$\begingroup\$ To get rid of the cartoon physics feel you could just rule that the material of the wall will only become thick enough to be supported by its base: Iron wall on top of a rickety shack would maybe cause it to complain but you'd end up with just a paper-thin wall of iron. Just a thought. \$\endgroup\$
    – JackChance
    Apr 16, 2018 at 21:44
  • \$\begingroup\$ That's not a bad idea, though it'd require some careful thinking and agreement between DM and players (how are non-wall structures like Wood Cabin affected?). The reason we use the rule in my answer is that, once accepted, it has generated fairly little discussion. \$\endgroup\$
    – mech
    Apr 16, 2018 at 21:56

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