[RPG] Can Spirit Guardians affect enemies through walls


We just had a scenario where the enemy set up a 'death trap' with arrow slits covering a corridor, allowing them to pop in, shoot, then pop out — all without actually entering the corridor. Which was fine in and of itself, until my cleric ran through the corridor at top speed, with Spirit Guardians up.

The DM and I discussed it, and as far as we can tell the spell doesn't require a line of sight and isn't blocked by walls — just being 'in range' gets you the damage. So I wiped out an entire encounter with one well placed third level spell. In and of itself, that doesn't seem too OP — at level 5/6 a third level spell is a pretty big investment! But it still seems a bit odd that I can do it without even LOS.

Are there any rules I'm missing?

Best Answer

Unless an AoE spell has a specific exception, it doesn't affect creatures through walls. To establish the type of spell Spirit Guardians is, we have the following:

Spells that create cones or lines of effect that originate from you also have a range of self, indicating that the origin point of the spell’s effect must be you (see “Areas of Effect” later in the this chapter).

Spirit Guardians has:

Range: Self (15-foot radius)

so it clearly fits into this category. The important rule here is on page 84 of the Player's Basic Rules (page 80 if you have an older version of the basic rules PDF), under the Areas of Effect section:

A spell’s effect expands in straight lines from the point of origin. If no unblocked straight line extends from the point of origin to a location within the area of effect, that location isn’t included in the spell’s area. To block one of these imaginary lines, an obstruction must provide total cover, as explained in chapter 9.

So if a creature has total cover from the point of origin, they're not affected by Spirit Guardians.

However, in this case, the targets can be affected if they're standing directly behind the arrow slit.

A target with three-quarters cover has a +5 bonus to AC and Dexterity saving throws. A target has threequarters cover if about three-quarters of it is covered by an obstacle. The obstacle might be a portcullis, an arrow slit, or a thick tree trunk.

So if the enemies are behind the arrow slits, they have three-quarters cover rather than total cover, and they can be affected by Spirit Guardians.

There is an additional potential issue with this strategy, but that was covered in this question.