BM stands for Battle Magic in Diablo, in other words the skill system. This was a very controversial topic because it introduced a skill point based skill system that wasn’t exactly the best system ever.
Formerly known as the “Effusion” system, it was changed to Battle Magic because it didn’t make sense to have a skill system with a “magic” theme. In fact, the game was even referred to as “BattleMagic” in some places.
Battle Magic has been revised several times, most notably in 1.2.0, where it was changed from an Effusion-based system to a more traditional point-based system. The first and only iteration of the Battle Magic system was very different from the current system. It had a different set of skills that were designed for a more class-based approach to Diablo.
Battle Magic was the first time that Diablo introduced the concept of “characters”. Before this, the only way to customize a character was through class and skills.
The idea behind Battle Magic was that each character had a certain amount of “magical power” (spell points) that could be used for any spell in the game.
However, the system was never completed. Blizzard ended up cancelling the project, and decided to start over from scratch with the current system.
The Battle Magic system features
Every character had a set amount of spell points. These points could be spent on any spell in the game. The more spell points a character had, the more spells they could cast.
Spells had a cost in spell points, and these points could be replenished by casting a spell.
There were two ways to cast spells: by using the mouse, or by using a keyboard.
There were also different types of spells. Each type of spell had a different range and could only be cast on certain targets.
Every spell had a “spell level”, which was the maximum level of the spell. Higher spell levels gave the character more powerful spells.
A spell could only be cast once every few seconds. This was to prevent spamming.
Characters were controlled using the mouse. The left mouse button was used to attack and the right mouse button to cast spells.
There were two main classes in Battle Magic: Mages and Warriors. Mages were a spell caster class, while Warriors were a melee class.
Mages could use any spell, while Warriors could only use melee spells.
There were three main classes in the original Battle Magic: Mages, Warriors, and Priests.
Only if a character could be both a Mage and a Warrior would they be allowed to use both melee and spell casting.
The three classes were:
Mages were a spell caster class. They could cast any spell, but they were restricted to melee spells.
Warriors were a melee class. They could only use melee spells.
Priests were a hybrid class. They could cast spells and they could use melee spells. There were also some sub-classes that were allowed to use melee spells:
Demonologists were a sub-class of Priests. They were allowed to use melee spells, but they had to have a “Demonology” level of the spell.
Werewolves were a sub-class of Priests. They were allowed to use melee spells, but they had to have a “Werewolf” level of the spell. Sorcerers were a sub-class of Mages. They were allowed to use melee spells, but they had to have a “Sorcerer” level of the spell.