Morals (Andu Supplement)
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A person is capable of doing anything given the right circumstance.
The idea of good or evil
A person who kills an innocent to save thousands of others could be considered a hero to many and a vile person to the relatives of the slain. The ends justify the means though it would be considered an evil act to the character and the relatives of the victim. The others may view him as a hero and good. Perhaps the character is charmed or tricked into killing an innocent. That may not be considered an evil act by the character. Others may perceive it as evil though. It is a matter of perception in this case.
A shot that goes wide and kills an innocent is a gray area. The character might feel remorse about it or believe it happened for a reason. A character that poisons an evil lords food which kills an innocent forced to taste test it could be deemed evil. The use of poisons can be conceived as an evil act depending on the expected outcome. If the max damage from primary and secondary would kill the intended target, then there may be grounds for evil intent. (i.e. primary and secondary damage is 1d6 Con, thus 12 Con damage would kill a common NPC)
There are many shades of gray with good vs evil. In this campaign the players may have to rely on an evil character for information or aid. The monsters and npcs may have the evil alignment but there are exceptions. It is very possible to find a good goblin or mind flayer adventuring.
Spells and equipment
Protection from evil or spells that have Good descriptor will harm evil monsters regardless of their intentions. Divination spells like Detect Good or Detect Evil might not pick up on these individuals because it hones in on the intention. Vile damage will harm good characters regardless of intention.