Can Spells Be Cast Through Complete Cover?

The rules of magic dictate that you cannot target something behind total cover, and an area of effect cannot go through total cover. To target something, you must have a clear path to it, so it cannot be behind total cover. If an area of effect is placed at a point that you can’t see and an obstruction, such as a wall, is between you and that point, the point of origin comes into being on the total cover.

To block one of these imaginary lines, an obstruction must provide total cover. However, the spell description does not specify when this area has to be established. For instantaneous spells like Sacred Flame or Scrying, casting through an illusory wall is generally not recommended, as it launches a bolt of force and doesn’t protect the warded creature from area effects.

When casting a spell with a casting time longer than a single Action or Reaction, you must spend your Action each turn casting the spell and maintain your Concentration while doing so. A target with total cover cannot be targeted directly by an attack or a spell, although some spells can reach such a target by including it in an area of effect. All spells are blocked by total cover, unless they explicitly can bypass it (like Message).

The rules concerning a clear path to the target state are found under the Targets heading of the Casting a Spell section. Most spells require you to be able to see the target, but only because the spells include that requirement in their text.

To block one of these imaginary lines, an obstruction must provide total cover. To target something, you must have a clear path to it, so it can’t be behind total cover like a solid wall. Casting spells requires a clear path to your target, so it can’t be behind total cover like a solid wall.

In conclusion, the core rules about cover apply to ALL spells, and any spell effect that makes it impossible to cast at someone or something behind total cover is not allowed.