I remember Mana Shield being OP a.f., and according to this guide, it actually got nerfed in Hellfire in a weird way, where increasing the spell level also increases the damage taken.
Not exactly. According to the Diablo patch notes, prior to v1.07, Mana Shield in Diablo also had this problem. Hellfire has it because it is a fork of Diablo v1.04, and the fix was not applied to Hellfire.
Mana Shield is EXTREMELY overpowered. If you combine it with the fact that if you have 30hp or less you don't get staggered when you get hit, well... :P
This is due to a design bug, and does not work exactly as you describe. Mana Shield does not redirect damage from life to mana. Combat still causes health loss as normal. Then, at the end of the turn, before the screen updates, the game notices that your character is protected by Mana Shield and refunds the lost health, charging you an appropriate amount of mana in return. That is a bit weird, but it probably seemed like a good idea at the time. The alternative would have been to modify every site that deals health damage to use a helper function to deal health/mana loss directly. The big problem is that the health-then-refund model breaks down when dealing with other special status effects. If your character takes damage greater or equal to character level, then you are stunned. However, if you take damage greater or equal to your current health, you are killed. Due to the implementation of Mana Shield, if you take fatal health loss, but have sufficient mana to cover the damage, then you should not actually die. Mana Shield satisfies this requirement by canceling your death state and putting you back in Stand state (instead of whatever state you would have had if the game had not declared you dead). If you were supposed to be in Stand state, you won't really notice a difference. If you were supposed to be in any other state, such as stunned, then you are in the wrong state after Mana Shield prevents your death. This leads to several exploits, all from the same bug:
- A character with health less than level can never be stunned. Damage less than level would not stun due to the normal rules. Damage greater or equal to level would kill the character instead of stunning him, then Mana Shield would cancel his death.
-- More generally, a character with current health less than the minimum damage of the attacking monster cannot be stunned, even if current health exceeds character level.
- A character cannot be knocked backward by an attack that deals fatal health damage.
- A character hit by simultaneous attacks may die from an early attack and ignore later ones.
This actually isn't true. I was playing on Hell difficulty with a sorcerer this morning and monsters were stun locking me, even with mana shield active.
Are you sure it was a stunlock and not a standlock? How much current health did you have?
//diablo.fandom.com/wiki/Patch_1.07_(Diablo_I) section "Medium bugs (affecting gameplay)" states:
- Fixed the bug that caused Mana Shield to become less effective with increasing spell level.