Why is it that Fallen Maniacs can kill me flat from 23k hp to zero when I have Energy Armor with Force Armor rune up? Is that even possible or did my Energy Armor decay without me realizing?
Assuming you didn't let Energy Armor decay, it's likely due to the Force Armor hotfix -
Amount of damage absorbed from a single attack will now cap at 100% of a player’s maximum Life.
Though this is poorly worded, this basically means that while Force Armor will trigger on any hit larger than 35% of your health pool, it won't absorb more than 100% of your life in damage - for example, with your 23,000 life, if you were to take a hit for 60,000 damage, Force Armor will attempt to reduce it to 35% of your total life - 8,050 damage. However, since it's not able to absorb more than 100% of your life, it can't reduce it below 37,000 total damage, thus killing you in one shot.