History of Spell Resistance?

[Nemitri]

I see this question pop a lot in here, people try to fix spell resistance in a way or another, some even question its existance, I don't want a solution, I just want to know the logic and reasons that what went behind the implementation of spell resistance.

[Distant Scholar]

Nemitri wrote:

I see this question pop a lot in here, people try to fix spell resistance in a way or another, some even question its existance, I don't want a solution, I just want to know the logic and reasons that what went behind the implementation of spell resistance.

It's at least as old as AD&D 1, although it was called "Magic Resistance" then, and was a percentage (that went up by steps of 5%) instead of a d20 roll. (So, it was probabilistically the same.)

As to why? Ask Gary Gygax. :-)

[thenobledrake]

In the olden days it was meant to represent a difference between a magical/supernatural/mythological creature and a mundane creature.

There might be say, an animal (like a dinosaur) a monster (like a troll) and a supernatural/magical creature (like an undead) that all had the same Hit Dice. Their combat abilities (THACO and Saves) were tied to the Hit Dice, so for the most part the "chasis" of the monsters would be the same... enter special qualities to start creating differences: the troll picks up regeneration and becomes more threatening than the dinosaur, and the undead needs something too - but not the same something, so he gets magic resistance.

Then, Magic resistance switched sides of the screen in 3rd edition and became something the player rolled and their level affected instead of a flat value % chance that the DM rolled to check.

[leo1925]

Here.

[see]

thenobledrake wrote:

and their level affected instead of a flat value % chance that the DM rolled to check.

Actually, in 1st edition, magic resistance was normed for the 11th-level caster, going up/down 5% by level difference. To quote the 1e Monster Manual, "Thus a magic resistance of 95% means that a 10th level magic-user has no possibility of affecting the monster with a spell, while a 12th level magic-user has a 10% chance."

It was in 2nd edition that it was made a true flat percentage value, and level no longer had any effect. 3rd edition represented a return to the 1st edition approach.