I'm going to be running a campaign about a city in the clouds.
I think a storm-based genasi might be appropriate for this setting.
Their baseline is +2 Con, 30 ft, Medium size.
For the Storm sub-race, I was thinking about the following:
+1 Dex. Storm genasi are quick as lightning.
Storm Sense. Storm genasi can see through clouds and mist without impediment. They have advantage on saving throws to avoid being blinded by bright light or deafened by loud noises.
Thunderbolt. When a storm genasi scores a critical hit, they do an additional die of damage, and this additional damage is thunder damage.
Does this seem fair and balanced? I'm also considering giving them thunder, and/or maybe lightning, damage resistance.
I think that's fine. I don't like the first part of Storm Sense because I feel it's kind of like the Warlock's Darkness/Devil's Sight combo, it'll probably never come up unless you make it come up, and then it screws everyone else over.
Other options I'd consider:
Cast Thunderwave or Shatter 1/day instead of Thunderbolt (I don't think big crits when I think of Storm Genasi).
Immunity to being moved around by winds + thunder or lightning resist (as you mentioned).
Alternatively, if keeping the bonus crit damage and making them hit as hard as a storm, change the Dex bonus to Str (to differentiate them from Air Genasi).
Another other option is giving them a Cha bonus as that's the only stat not yet covered by Genasi subraces, and there's a Storm Sorcerer archetype.
Yeah, I was thinking of a Cha bonus. I really like the Storm Sorcerous Origin, too. A Cha bonus would work for scary barbarians, loud bards, storm of vengeance paladins, warlocks, and sorcerers.
Maybe give them advantage on Stealth checks when hiding in clouds and mist?
The campaign is going to be featuring a fog-shroud city (think London on steroids) above a permanent thunderstorm they will probably be flying and traveling through a lot, and end up near volcanos, steamy jungle, foul swamp gases, and the like.
Gust of Wind could also be a level appropriate spell and allow them to blow away said fog for this campaign, without locking them into an otherwise pretty rare to come up ability.
Gust of wind seems like a good alternative to the air genasi's levitate trait, but it doesn't seem thunderstormy.
I thought about shocking grasp at 1st level and then shatter or witchbolt at 3rd or 5th level, but that seems too blasty, even if the fire genasi get something equivalent.
It looks like genasi with +1 to physical ability scores get 2 traits, the one that gets the +1 to the uncommon mental save ability score gets 3 really good traits, and the one that gets the +1 to the common mental save ability score gets 4 good traits.
So.....
A +1 Cha can have 3 racial traits, since it is an uncommon mental save ability score. :-P
Maybe:
Thunder resistance.
Advantage on saving throws and ability checks to avoid being moved or made prone.
And my original Thunderbolt trait? It's similar in power to the half-orc trait, except the extra damage is thunder damage, and it would work for spell attacks and weapon attacks, so all kinds of classes could benefit from it.
My only concern is all 3 are pretty circumstantial.
Would thunder and lightning resistance be too much?