Magic Damage is a type of Elemental Damage in Diablo I and Diablo II. In Diablo III, it was replaced with Arcane and Holy damage.
Diablo I examples include:
Zombies and Skeletons were also immune to magic on all difficulties.
In Diablo II, it is named as Magic Damage on unique items like Azurewrath, and Magic Resistance 5-10% in Crafted Safety Shield, this shield is the only way to get Magic Resistance, which is not shown on the stats screen. While much more common as a monster resistance/immunity, it's still one of the rarest. Just like in Diablo I Magic Attacks don't have a specific color assigned to them, they can be black, white, blue and red, with magic immunity text on monsters being orange.
List of Monsters using magic damage in Diablo II:
- Greater Mummies (all types) - unholy bolt,
- Doom Knights - as a random melee element,
- Abyss Knights - white orb throwers, also randomly in melee,
- Oblivion Knights - white orb throwers and Bone Spirit,
- Diablo - Cold Touch attack,
- Succubus and Stygian Fury (all types) - melee attacks and blood stars,
- Guest Horror Archers - random arrow damage,
- Guest Claw Viper, Pit Viper - Bone Spear attack,
- Guest Serpent Magus - all attacks,
- Baal - Mana Rift attack,
- All uniques and super-uniques that have Spectral Hit can also randomly deal magic damage.
Magic damage was also represented by the color white or light blue in many class skills.