I'm researching ahead of the (potentially) final battle in Curse of Strahd (as the DM)

One of the tactics the party is discussing is trapping Strahd in a wall of force, and then exposing him to the sunlight shed from the sunsword.

Per the Sunblade description

The sword’s luminous blade emits bright light in a 15-foot radius and dim light for an additional 15 feet. The light is sunlight. While the blade persists, you can use an action to expand or reduce its radius of bright and dim light by 5 feet each, to a maximum of 30 feet each or a minimum of 10 feet each.

And per the stat block for Vampires

Sunlight Hypersensitivity. The vampire takes 20 radiant damage when it starts its turn in sunlight. While in sunlight, it has disadvantage on Attack rolls and Ability Checks.

There's a great discussion on what constitutes sunlight exposure to a Vampire here (short version - if Strahd can see the Sunsword, and he's in range of its light, he's in sunlight)

But under normal circumstances, no spell can penetrate a Wall of Force (discussed here) but this is a weird grey area where this is really just (admittedly) magical light triggering a vampire's sunlight hypersensitivity.

So the sunlight isn't a spell, per se. But on the flip side, Strahd has the equivalent of total cover, but not total concealment.

So is the answer "nothing gets through a wall of force" or is the answer "The sunlight sensitivity is a pre-existing condition that's trapped inside the wall of force" or am I missing something else about concealment vs. cover.

Thanks in advance!


2 Answers 2


A wall of force does not block light. This is what it means to be invisible.

A wall of force is invisible. This means that light from one side passes through it to the other side.

Now we should also address this phrase from the spell description:

Nothing can physically pass through the wall.

I’m rather confident that the authors of the rules did not expect us to need to discuss the particle-wave theory of light when ruling on spells. When the spell description says “physically”, it seems abundantly clear that we are talking about tangible, material objects, which light is not.

Light should be able to pass through the wall just fine, and your Strahd-kebab will be ready shortly.

  • 2
    \$\begingroup\$ Of course, Strahd can just cast Fog Cloud on his side of the wall, and block the sunlight. Also he can Charm through the wall just fine. \$\endgroup\$
    – Marq
    Commented Sep 20, 2021 at 8:34
  • \$\begingroup\$ I think the logic of this answer "Invisible is the very definition of permeable to light"is good enough for me. \$\endgroup\$
    – Σ of eDπ
    Commented Sep 20, 2021 at 18:30
  • \$\begingroup\$ @Marq Fog cloud makes for a great defense. But given the ruling that spells can't transit even a window, (let alone a wall of force) he won't be able to charm anyone outside the wall. ref: rpg.stackexchange.com/questions/59734/… \$\endgroup\$
    – Σ of eDπ
    Commented Sep 20, 2021 at 22:45
  • 1
    \$\begingroup\$ @SumofeDpi The vampire's charm ability isn't a spell, and only requires that the vampire and the target can see each other. There's no reason for a wall of force to block it. \$\endgroup\$
    – Marq
    Commented Sep 21, 2021 at 11:59
  • \$\begingroup\$ Fair point @Marq. It's in that "spell-like ability" grey area as well. Out of curiosity, do you think counterspell would work through a wall of force? I'd argue "yes" because it's one of the few spells that doesn't specify a target. Plus it's abjuration magic, and that seems to ignore rules for cover (and etherialness) \$\endgroup\$
    – Σ of eDπ
    Commented Sep 22, 2021 at 18:39

I would say "no", and rule that the Wall of Force, that blocks all magical effects, would protect him from the effects of magically sunlike light, if the Sunblade is outside the Wall.

Now, if you Wall of Force him outside in the natural sunlight, that would work (except Ravenloft is perpetually clouded and gloomy for a reason).

If you cooperated to load up the person carrying the Sunblade with defenses, and trapped them both in the Wall of Force, hoping that the wielder survives long enough for the sunlight to kill Strahd, that would be valid.

But Wall of Force and Sunblade/Sunlight spell/etc. does not make a guaranteed safe kill. (Not to mention that if Strahd has any teleport ability, even just Misty Step, he can escape and evade this.)

  • 3
    \$\begingroup\$ Could you include a quote and source for this “wall of force blocks all magical effects” rule? I’m not aware of such a rule and it is definitely not in the spell description, which states that it blocks things from “physically” passing through. \$\endgroup\$ Commented Sep 18, 2021 at 23:04
  • \$\begingroup\$ I suppose you could play that it does not block magic, in which case the standard tactic for any party with a level 9 wizard will be to cast a Wall of Force dome over the party, and fire out all the spells that target creatures you can see, and there's nothing the targets can do about it. I've never seen a table play that way. \$\endgroup\$
    – PhilB
    Commented Sep 19, 2021 at 1:04
  • \$\begingroup\$ The only controversial part is that Wall of Force blocks magical effects, and we discussed that above. Other questions and answers address that controversy. One of the least appealing parts of this site is how much and how often y'all micromanage everyone's questions and answers. \$\endgroup\$
    – PhilB
    Commented Sep 19, 2021 at 14:21
  • \$\begingroup\$ @ThomasMarkov Does your own (admittedly unofficial) answer from a post linked in the question count? rpg.stackexchange.com/a/59741 For the record, I think this is a great question, and one that each DM can interpret slightly differently. For example, if magical light is not permitted through, then why teleportation? Wall of Force seems to break even more physics than most parts of D&D. :) I like this answer's perspective, since it at least attempts to hold "magical effects" together as a standard, whether generated by a spell (does sunlight from control weather count?) or a magic item. \$\endgroup\$
    – 3d12
    Commented Sep 19, 2021 at 20:11
  • \$\begingroup\$ @3d12 That’s not my answer, I think that answer is mostly useless. \$\endgroup\$ Commented Sep 19, 2021 at 20:13

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