Guns that shoot different kinds of bullets at different speeds depending on what clothes the wielder is wearing.
People can wield soulbound magic that will transfer to whoever kills them. However, this magic can be rigged by mages to the killer’s detriment, too.
Your protagonist is a beggar who seems to possess an ability to get lots of money from people, more than any other beggar. People try to discover and take this ability. As it turns out, however, it’s a combination of elements, such as cats liking him and being around all the time, a kind face, a pleasant smell, etc.
A type of precipitation that explodes on impact with the ground. To make it even more interesting, have the explosions consist of something other than fiery death. Maybe cats or something, like wind or flowers.
A certain race of people has a high chance of being born mute, but in turn, they’re more naturally attuned to music and sound than normal folks.
A magic system in which anger, jealousy, greed, and all other sorts of negativity produce healing, resurrection, and supportive spells, while positive emotions like love produce fireballs and stuff.
People actually have “levels” like in role-playing games that show above their heads at all times based on their life experience. This, rather than age, is used to determine things like job qualifications.
Magic based on statistics wherein every spell cast has several possible outcomes with no way to regulate them (rather than cast or don’t cast).
Thousands of people have the ability to walk on water, but can’t swim. They build entire civilizations on water, separate from their same species on land.
The evil overlord’s plan to destroy the world is foiled when his right-hand man sabotages all of his bombs to explode out greenery and life and pretty things rather than just blowing shrapnel everywhere.