I see that NKarmaPot and PKarmaPot are almost exactly identical.  I think you can get away with one class, in the following way:

- Call the class KarmaPotion (no need to abbreviate).
- Make a positive/negative boolean constructor argument.
- Include resources for the words "positive", "negative", which are chosen at runtime based on the positive/negative property set from the constructor.
- Karma is set to + or - depending on the value of the property.