Healthbar animation for Magic Shields is misleading
When you take damage in League, a portion of your healthbar changes to red, and then shrinks, so it is easier to see what portion of your health you have lost.
However, this has some misleading implications when magic shields are on champions. When you take physical damage with a magic shield up, the portion of the healthbar where your actual health is should light up red and shrink, signifying that you lost your actual health. Instead, the red part of the healthbar is to the right of the blackshield, making it seem like you took magic damage.
Taking magical damage with blackshield Taking physical damage with blackshield