Elemental Magus (a DND 5e Homebrewed Wizard subclass inspired by @comicaurora)
DISCLAIMER:
This is straight-up unbalanced. Balancing was always a secondary concern, because that's not what I like about making these, but this time, it's bad enough that even I can't see past it. However, I don't know exactly how to balance it properly while keeping the things I like about it, so I'm freeing this from my drafts and letting the ideas out so someone else (possibly future me) can retool it into something that won't make your GM rip out their hair in frustration. Anyway, I hope you enjoy the subclass all the same !
EDIT: Did my best to rebalance it. Let me know what you think !
2nd level: Such A Lofty Title
Starting at 2nd level, you are revealed as an Elemental Magus, an extremely rare kind of mage that can command all six Primordial elements: Fire, Life, Lightning, Stone, Water, and Wind.
You can now copy spells that deal fire, necrotic, lightning, bludgeoning, cold, or thunder damage as well as healing spells into your spellbook, even if they are outside of the wizard spell list. Your spellbook can only contain a number of these spells equal to your proficiency bonus. You cannot learn these spells as part of leveling up, and cannot choose them for your Spell Mastery and Signature Spells features.
2nd Level: Just Another Problem to Solve
At 2nd level, your intense study of the mechanics of elemental magic has allowed you to supplement your spells with the properties of the elements. Depending on the damage a spell deals, you can choose to add an additional effect to the targets of your wizard spell in function of the element used:
Fire: One target of your choice must succeed on a Dexterity saving throw or take 1d6 fire damage at the start of their next turn. Anything that would douse a regular fire stops the condition.
Necrotic: One target of your choice must succeed on a Constitution saving throw or have their hit points maximum reduced by your proficiency bonus + the spell's level. This effect is not cumulable with other reduction of maximum hit points, including another use of this feature.
Lightning: One target of your choice must succeed on an Intelligence saving throw or be unable to take a reaction until the end of your next turn.
Bludgeoning: One target of your choice must succeed on a Strength saving throw or have their speed reduced by 15 until the end of your next turn.
Cold: One target of your choice must succeed on a Dexterity saving throw or have disadvantage on their next attack roll.
Thunder: One target of your choice that is either concentrating on a spell or has activated a feature that ends on certain conditions or the target's will (such as a Barbarian's Rage or a Druid's Wild Shape), they must succeed on a Concentration saving throw against your spell save DC. On a failure, they drop concentration on their spell or their feature deactivates.
You can use this feature a number of times equal to your Intelligence modifier (minimum of 1).
6th level: Safety Is By Definition Not Overcomplicated
At 6th level, you’ve mastered the technique of rune casting, at the cost of the speed of intuition-based magical forms. When you cast a spell that deals fire, necrotic, lightning, bludgeoning, cold, or thunder damage, you can choose to use a runic circle for the spell. When you do so, your spell takes effect at your initiative minus 10, and any roll the spell asks for (damage rolls, saving throws, attack rolls, concentration checks …) can be granted advantage. Additionally, if the spell requires you to use your action to keep an effect of the spell going, you can instead use your bonus action.
If the spell affects an area of effect, you can move it a number of feet equal to five times your Wisdom modifier (minimum of 5) as it takes effect. If the spell affects a single target and said target moves away from your range of casting, the spell fails and you waste a spell slot.
If used outside of combat, the spell takes effect after 10 minutes instead.
10th level: Phenomenal Natural Talent
Starting at 10th level, you can use your command over the elements to shield you and your surroundings from their effects. On your turn, you can use an action to expend a spell slot and summon a 10 ft. sphere of protective elemental energy centered on yourself for a minute.
When you use this feature, you must choose one type of damage from the following list: bludgeoning, cold, fire, lightning, necrotic, or thunder. You can nullify the effect of one spell dealing that type of damage per round. The spell must be cast at no more than two levels above your expended slot.
While this feature is active, you are considered as concentrating on a spell for all intents and purposes. Once you use this feature, you can't use it again until you finish a long rest.
14th level: A Primordial True Name in Its Purest Form
At 14th level, you learn the true name of the Elemental Primordials. As a result, you can now invoke the higher property of one of the elements during combat in order to control the battlefield.
Fire/Transmutation: As an action, you can choose a creature within range, which must make a Constitution saving throw. On a failure, you can choose to transform one resistance, vulnerability, or immunity from one type of damage to another for the duration. The target can choose to fail the saving throw.
Life/Survivability: If a creature fails their last death saving throw or takes enough damage to die on hit within range, you can use your reaction to temporarily stop them from dying. If the creature is healed or stabilized while their death is being halted, their hitpoints remain at 0, but the creature will instead be unconscious and stable instead of dead or dying, and your Life effect ends.
Lightning/Connection: As an action, you can choose two willing creatures, including yourself, within range. of you in order to link them. When one of the linked creatures takes damage before the end of the effect, the other can choose to take half of the damage instead of their ally.
Stone/Loyalty: As an action, you can choose a spell caster within range to let them to temporarily use your spell slots for their own spellcasting. When your ally uses one of your spell slots, both of you take 1d10 necrotic damage. This damage cannot be reduced in any way.
Water/Flexibility: As an action, you can allow up to three willing creatures within range other than yourself to make an action become a bonus action instead for the duration.
Wind/Communication: As a bonus action, you can choose a creature within range and force them to make a Charisma saving throw. On a failure, their allies are now temporarily hostile towards them. The target can use their action in order to try and convince their allies that they aren’t an enemy, repeating this saving throw. Creatures immune to the charmed condition will not turn hostile.
Each of these effects lasts for a number of turns equal to your Wisdom modifier and you are considered as concentrating on a spell for all intents and purposes while they are active. Once you use one of these features, you can't use any of them again until you finish a long rest.
