# If I have 100 ad and my opponent has less than 0 armor, will I deal more than 100 damage? [duplicate]

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 `0`, physical damage will be amplified. There exists a simple formula for the damage multiplier:
`damage multiplier = 2 - 100 / (100 - armor)` [​1]
For example, at `-100` armor, the damage multiplier is `2 - 100 / (100 - (-100)) = 2 - 100 / 200 =``1.5x`. Therefore, an auto attack with `100` AD against a target with `-100` armor (and without the relevant defensive masteries) will do `1.5 * 100 =``150` damage.
Theoretically, as you reduce an opponent's armor more and more, you will approach a `2x` damage multiplier. In practice, however, you will rarely see enemies with less than `-30` armor, which gives a `1.23x` damage multiplier.
As Hackworth mentioned, it is also possible to have negative magic resistance. (For instance, super minions have `-30` base MR.) Magic resistance uses the same formula as armor for calculating damage multiplier.