I'm constructing a homebrew setting for a campaign in which elemental magic is much more common than in most D&D official settings.
There will be portals to the elemental planes and elemental creatures will be a common feature in the world.
To add flavour to the campaign, I want to provide adventurers (regardless of class) access to a few elemental features. I called it Elemental Affinity.
I intend to allow the players to choose one of the elements: air, earth, fire or water. Once chosen, they will not be able to change their chosen element – as, thematically, this will be something they would have grown up with as creatures born in this world.
I'm of two minds about providing this feature to NPCs from humanoid races and/or bosses but I think it would add flavour and a counter-balance perhaps, e.g. the leader and second-in-command of a large band of orcs may be Barbarians with an affinity to earth.
This is what I intend to provide my each of the players, for my homebrew:
Choose an element to which you have an affinity: air, earth, fire, or water. As you progress, your PC will acquire certain features depending on your overall character level.
Elemental Manipulation: At 1st Level you learn a Cantrip that does not deal damage and is associated with your elemental affinity:
- (air) Gust (XGE, p.157)
- (earth) Mold Earth (XGE, p.162)
- (fire) Control Flames (XGE, p.152)
- (water) Shape Water (XGE, p.164)
Elemental Bond: At 7th level, you can tap further into your elemental affinity. In combat, you can use your reaction to use this feature; this lasts until the end of your next turn. You can use this feature up to 3 times and you regain all your expended uses of Elemental Bond when you finish a long rest.
- (air) Resistance to lightning and thunder
- (earth) Resistance to poison; advantage on saving throws against petrification
- (fire) Resistance to fire
- (water) Resistance to cold and acid
Elemental Weaver: At 11th level, your connection to the elements becomes such that you begin to understand the very fabric of elemental magic. You learn a 6th-level spell associated with your elemental affinity. Once you have cast this spell, you regain the ability to do so when you finish a long rest. This feature does not use a spell-slot or count towards the total number of spells you know. (XGE, pp.159-160)
- (air) Investiture of Wind
- (earth) Investiture of Stone
- (fire) Investiture of Flame
- (water) Investiture of Ice
Note: Your spellcasting ability for the spell depends on your class: Charisma for bard, paladin, sorcerer, or warlock; Intelligence for artificer, wizard, fighter (eldritch knight, arcane archer, psi warrior), or rogue (arcane trickster); Wisdom for cleric, druid, monk or ranger. If you have more than one spellcasting ability, you choose which one to use for the purposes of this spell. If you are a melee class without a spellcasting ability, then use: Constitution for Barbarian or Fighter; Dexterity for Rogue.
Is allowing my players to have access the Elemental Affinity features (cantrips, resistance and investiture spell) likely to create any serious balance issues in the game - and potentially ruin the whole campaign?
What is a good answer?
For the purpose of an answer, it would be helpful if it followed the Good Subjective/Bad Subjective rule. I am looking for answers from DMs who have implemented a similar feature in their campaigns, or can see some obvious traps.
If you suggest an adjustment/substitute for one of the Elemental Affinity features for the purposes of rebalancing, please explain the reasoning behind it, too.