Can an area of effect spell be cast through total cover?

Question

Wall of Ice was cast across a field. My player wanted to cast Storm Sphere on the other side, even though there was no clear path to the target.

I told her that as there was no clear path, so she couldn't cast the spell. She said that because she could choose where it went, and the place was within range, she could cast it because of the wording of the spell.

Most of what I had seen would say that she could not cast the spell. I had looked up a spell with similar wording, and had gotten the impression that while line of sight was not necessary, there had to be a clear path.

I don't really like saying no, but I also think that the ability to cast an AoE spell through a solid barrier seems pretty unbalanced.

Was my ruling correct?

Answer 1

Your ruling is almost correct.

The rules concerning a clear path to the target state:

To target something, you must have a clear path to it, so it can't be behind total cover.

If you place an area of effect 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 near side of that obstruction.

Since storm sphere is an area of effect, its point of origin should come into being on the near side of the wall of ice. To be technical, it is not that she cannot cast the spell, rather, she can cast the spell, but it does not come into effect where she wants it to.

There is an alternative you could have presented.

The wall of ice is only 10 feet tall, and the radius of storm sphere is 20 feet, so it is conceivable that a sphere placed in the air on the other side of the wall could have the desired effect. Though, your mileage may vary based on the form of the battlefield.