Thanks to another DDB user asking about Tritons and Darkvision, I got to thinking that, actually, a lot of stuff functions differently underwater than on land. Many animals rely on different senses. Spells that affect air or create fire become virtually useless.
Example: Lateral Lines. Most fish have an organ that runs the length of their bodies that allows them to detect movement in water. This is necessary b/c water easily becomes murky, so vision is less reliable. Without lateral lines, fish probably could not move in the coordinated patterns that we witness in documentaries about nature. Ancient, lone predators like sharks also have this organ, implying that it evolved a very long time ago and is helpful to hunting. Anyway, perhaps most fish and underwater-origin races should have something like Tremor Sense that lets them detect the location of creatures within a certain radius of themselves that only functions when both creatures are immersed in water. This has other implications, of course. It means that the Invisibility spell actually should not function the same way in close range while fighting most aquatic-adapted creatures underwater. Dolphins could see you via echolocation. Sharks could both smell and "hear" you via their lateral lines. Invisibility would, however, still kind of work versus crabs or giant octopi since they have no organs for hearing.
What spells or abilities would make sense in a fully underwater campaign?
And are there books from older editions that would help with this?
Aquatic creature could have been sense just with blind sight and if both are in the water. There was older additions that did things like lightning bolt cast into or underwater pretty much turned the AOE line into a AOE radius like fireball. Other than that, being in water does give resistance for fire.
I think the interesting thing about magic underwater would be that all spells are cast, but what happens might be unexpected. For instance, a cone of cold works, but leaves behind an ice cone, which may trap creature who fail a save. Gust of wind creates a wall of bubbles, obscuring vision (or whatever senses are used).
Of course, these effects are DM dependent, and you may want to discuss them first, but taking out a merchant ship from below with a cone of cold size piece of ice slaming into the hull sounds pretty cool.
Thanks to another DDB user asking about Tritons and Darkvision, I got to thinking that, actually, a lot of stuff functions differently underwater than on land. Many animals rely on different senses. Spells that affect air or create fire become virtually useless.
Example: Lateral Lines. Most fish have an organ that runs the length of their bodies that allows them to detect movement in water. This is necessary b/c water easily becomes murky, so vision is less reliable. Without lateral lines, fish probably could not move in the coordinated patterns that we witness in documentaries about nature. Ancient, lone predators like sharks also have this organ, implying that it evolved a very long time ago and is helpful to hunting. Anyway, perhaps most fish and underwater-origin races should have something like Tremor Sense that lets them detect the location of creatures within a certain radius of themselves that only functions when both creatures are immersed in water. This has other implications, of course. It means that the Invisibility spell actually should not function the same way in close range while fighting most aquatic-adapted creatures underwater. Dolphins could see you via echolocation. Sharks could both smell and "hear" you via their lateral lines. Invisibility would, however, still kind of work versus crabs or giant octopi since they have no organs for hearing.
What spells or abilities would make sense in a fully underwater campaign?
And are there books from older editions that would help with this?
Aquatic creature could have been sense just with blind sight and if both are in the water. There was older additions that did things like lightning bolt cast into or underwater pretty much turned the AOE line into a AOE radius like fireball. Other than that, being in water does give resistance for fire.
I think the interesting thing about magic underwater would be that all spells are cast, but what happens might be unexpected. For instance, a cone of cold works, but leaves behind an ice cone, which may trap creature who fail a save. Gust of wind creates a wall of bubbles, obscuring vision (or whatever senses are used).
Of course, these effects are DM dependent, and you may want to discuss them first, but taking out a merchant ship from below with a cone of cold size piece of ice slaming into the hull sounds pretty cool.