This question already has an answer here:
Or is it capped to 100? If it is, is there a point to go below 0 armor?
Any time you manage to reduce an opponent's armor to below
For example, at
Theoretically, as you reduce an opponent's armor more and more, you will approach a
As Hackworth mentioned, it is also possible to have negative magic resistance. (For instance, super minions have
Yes, negative armor/magic resistance can happen and will have the same effect as positive armor/mr, except it increases damage. For example, 100 armor halves physical damage, -100 would double it.