Diablo 1 HD Hellfire Mod | Awake

So I'm a sorcerror in Nightmare. I'm versing this zombie which is lightning enchanted. Sometimes when a single lightning bolt hits me (he shoots charged bolt when hit) I die despite having 100% hp and 50%+ mana left.

Does manashield sometimes not block damage? If so and thats intentional, it seems like a massive balance issue if 100% oh my hp cannot withstand a single charged bolt missle. I only have 100 HP but I have 54% lightning resist. I should not be dying. Whats more strange is that these missles do negliable damage to my mana, but takes ALL of my hp (when manashield fails). It seems glitchy. About 1 in 10 charged bolts will kill me instanly.

If the devs need to know, the name of the unit is "Filth the Flayer". He's a Behemoth and Lightning Enchanted, orange coloured zombie.

Edit: Tried fighting without mana shield. Seems the charged bolts do 0 damage to me. Yes not even 0.1 damage. However, the 1 in 10 charged bolts kill me instanly regardless of remaining HP. It's definately bugged somehow.

There are definitely some form of attack(s) that bypass manashield... Either by design or bug I'm not sure. I haven't quite been able to put my finger on it though.

1 hit kill with full mana and mana shield up.

I've just been moving forward cautiously when I see the tags I don't fully understand, IE: Behemoth, Bloodlust, Mastery etc...

Behemoth - increased hp and armor
Mastery - increased hit Chance
Bloodlust - increased damage based on target hp %. (target at 10% hp = 90% more damage)

Thing you described is some rare bug related to monster reflective abbilities like lightning enchant/posion. Hopefully can be fixed