Does Complete Cover Neutralize Every Pathfinder Spell?

In 5e, line of sight is a concept, meaning that if you have no total cover, no spell should work on you unless it’s specified otherwise. If you don’t have line of effect to your target, you cannot draw any line from your square to your target’s square without crossing a solid barrier. This means that you can’t make an attack against a target with total cover.

AoE spells would work normally, but cover grants you a +2 bonus on Reflex saves against attacks that originate or burst out from a point on the other side of the cover from you. To block one of these imaginary lines, an obstruction must provide total cover. Cover applies only if your path to the target is partially blocked. For an instantaneous spell like RAW Fireball, cover applies only if there is a path fully within range of the effect that can reach the target.

Total cover can’t be targeted directly by an attack or a spell, although some spells can reach such a target. Cover applies only if your path to the target is partially blocked. If a creature is entirely behind a wall or the like, you don’t have line of effect and typically can’t target it at all.

Using a tower shield for cover negates its AC bonus. A cover that wraps around the entire body could provide cover against spells with a bending line of effect. A burst spell affects whatever it catches in its area, including creatures that you can’t see. It can’t affect creatures with total cover from its point of view.

Line of sight is a thing in 5e, so if you have none aka total cover, no spell should work on you unless it’s description says otherwise. The shield does not provide cover against targeted spells; a spellcaster can cast a spell on you by targeting the shield you are wearing.