I've given a lot of thought to the way elemental damage type effectiveness tends to work in RPGs and a few other games. I figured a journal to share my thoughts and my recent decision for most of my upcoming game projects. You have your four classic Greek elements of fire, water, air, and earth. This can create a nice set of two pairs of "opposites" for thematic reasons; monsters/characters aligned with one element are the opposite of those aligned to the other. Fire is hot, water is cold. Fire is impulsive, water is restrained. Air is flighty and undisciplined, earth is staid and stable. Where pairs of opposites don't work well is in gameplay fun or balance. If opposites do double damage to each other - fire double to water but also water double to fire - then fights between the two don't really fit elemental differences as a theme, but just get over quicker. If you have eight elements of Fire, Ice, Water, Air, Earth, Lightning, Light, and Darkness but each one only interacts with