Prism Armor reduces the damage taken from super-effective attacks by 25% and is unaffected by abilities like Mold Breaker, Teravolt, or Turboblaze.
For example, a Dark-type move against a Psychic-type Pokémon with Prism Armor would deal 1.5× the usual damage instead of 2×. Similarly, a double weakness would be reduced from 4× to 3×.