House Rules/Home-brew Rules for magic

[Druss_the_Legend]

1. Do you have any house rules for how magic works in your game?
2. What home-brewed rules (if any) have you included in your campaign?

[Druss_the_Legend]

iv made some sweeping changes to the way magic works in my campaign. Understandably these changes may not be suited to your game world. My motivation was to make magic more unpredictable and potentially more dangerous to use. These home-brewed rules will evolve over the next year or so of playtesting. To account for these changes 'in game' the campaign story has taken on a darker tone with the recent appearance of a mysterious Dark God. The gods supporters are using a small number of legendary artefacts to called Soul Stones to open a doorway to a new dimension where magic operates differently. This rift between the two worlds has caused large disruptions in the flow of essence and has had an effect on all realms of magic. Over time I may differentiate some of these changes with different effects for each realm of magic (Essence, Channeling, Mentalism and Arcane)

Heres how it works...

Chaos Magic
Whenever any spell is cast, an Arcane Check is made. On a 21-80 result, the spell is cast normally. On a 01-20 a Bane effect results (see Bane Table) or on a 81-100 a Blessing results (See Blessing Table)

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
1d100 Arcane Roll
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
01-20 Bane effect (roll 1d10 on the Bane Effects table)
21-80 Spell is cast as normal
81-100 Blessing effect (roll 1d10 on the Blessing Effects table)
01-05* Spell Fumble, in addition GM chooses one bane affect (see below)
96-100 Player chooses one blessing effect (see below)
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

**Casters select 1 spell list as a mastery list. All Arcane rolls using a mastery list have advantage)**
*Spell Fumble range is 01-02 for any spell from the casters mastery list.

Bane Effects (Roll 1d10)
Mana Surge (Chaos)
Arcane Overload
Wild Magic Surge
Mana Drain
Divine Disfavor
Magic Fatigue
Elemental Recoil
Arcane Exhaustion
Corrupted Spellcasting
Spell Backfire

Blessing Effects (Roll 1d10)
Mana Surge (Law)
Arcane Resonance
Elemental Affinity
Magical Insight
Divine Favor
Spell Amplification
Arcane Shield
Elemental Infusion
Mana Recovery
Arcane Overflow

(Bane #1)
Magical Fatigue (Reduced Spellcasting Ability)
Effect: The caster feels drained after casting a spell, reducing their spellcasting potential. For the next spell cast, they suffer disadvantage on the attack roll and any target RR by the target has advantage.
Duration: Until the next spell is cast or for 1 minute.

(Bane#2)
**Arcane Overload (Spellcasting Disruption)**
- **Effect:** After casting this spell, the caster experiences a moment of instability, causing them to suffer disadvantage on concentration checks. Make a hard maneuver action or you are stunned 1 round. You may not cast another spell until you succeed in this action or until 3 rounds have passed (which every comes first)
- **Duration:** 3 rounds

(Bane #3)
**Wild Magic Surge (Chaotic Spell Effect)**
- **Effect:** After casting a spell, the caster triggers a wild magic surge, causing an unpredictable magical effect. Make a spell fumble roll and add the PP used to cast the spell to the roll.
- **Duration:** Immediate.

(Bane #4)
**Mana Drain (Reduced Spell Capability)**
- **Effect:** After casting a spell, the caster suffers from a temporary depletion of their magical energy, losing 3x the PP used to cast this spell. Additionally the caster is unable to cast spells of level 1-5.
- **Duration:** Until the next rest/meditation.

(Bane #5)
Divine Disfavor (Loss of Deity's Blessing)
Effect: If the caster is a divine spellcaster, their deity temporarily withdraws their favor. The caster suffers disadvantage on their next spell attack or RR. They also lose access all spells on this spell list until they regain favor (GM assigns a specific action or atonement).
Duration: Until the next rest/PP recovery.

(Bane #6)
**Magic Fatigue (Physical Fatigue)**
- **Effect:** After casting a spell, the caster becomes physically drained. They suffer disadvantage on their next attack roll or ability check and may be unable to take reactions for the next round.
- **Duration:** Until the end of the caster's next turn.
- **Example:** "The strain of casting takes its toll on your body, leaving you winded and slow to react."

(Bane #7)
**Elemental Recoil (Environmental Damage)**
- **Effect:** If the spellcaster casts an elemental spell (e.g., fireball, lightning bolt), they experience backlash from the magic's energy. They take a small amount of damage or suffer environmental penalties (e.g., smoke, blinding light). Cater takes an A critical (heat, cold or electricity = GM's choice)
- **Duration:** Until the end of the caster's next turn.

(Bane #8)
**Arcane Exhaustion (Exhaustion Penalty)**
- **Effect:** The spellcaster becomes exhausted from overcasting or using a spell that requires a heavy expenditure of magical energy, lose 3x the PP needed to cast this spell. These PP are not recoverable for another 48hrs.
- **Duration:** Until the caster takes a short or long rest.

(Bane #9)
**Corrupted Spellcasting (Tainted Magic)**
- **Effect:** The caster's magic becomes unstable or corrupted, causing the next spell they cast to have unintended side effects, such as reduced effectiveness, altered targets, or unintended consequences (e.g., healing spells causing necrotic damage).
- **Duration:** 1 spell (until the next spell cast).

(Bane #10)
**Spell Reversal (Backfire)**
- **Effect:** The caster's spell briefly backfires, causing them to take an A Shock critical or suffer 1-3 rounds of stun,
- **Duration:** 1 turn

(Boon #1)
**Mana Surge (Increased Spellcasting Potency)**
- **Effect:** After casting a spell, the caster gains a temporary boost to their spellcasting ability. Choose one: gain advantage on your next spell attack roll or increased damage for the next spell cast within the next minute.
- **Duration:** 1 minute.

(Boon #2)
**Arcane Resonance (Improved Spellcasting Accuracy)**
- **Effect:** The spellcaster's connection to the arcane deepens temporarily, only 50% concentration is required for any spells cast in the next hour.
- **Duration:** 1 hour

(Boon #3)
**Focus of the Elements (Elemental Affinity)**
- **Effect:** After casting an elemental spell (fire, cold, lightning, etc.), the caster's next spell of the same element deals double extra damage and an additional critical of one less severity.
- **Duration:** Until the next spell of the same element is cast or one hour whichever comes first.

(Boon #4)
**Wisdom of the Arcane (Magical Insight)**
- **Effect:** The spellcaster gains a moment of clarity, granting them a 3 PP and a temporary +10 bonus to their PR. EM or INT. - **Duration:** 10 minutes

(Boon #5)
**Divine Favor (Blessed Spells)**
- **Effect:** A divine spellcaster may feel their deity's blessing after casting a spell, which grants them advantage to RRs and resistance to physical damage (take half damage) for a short time.
- **Duration:** 10 Minutes

(Boon #6)
**Echo of Magic (Spell Amplification)**
- **Effect:** After casting a spell, the magic within the caster reverberates, causing their next spell of the same school or type to be amplified, either increasing its range or its area of effect (players choice).
- **Duration:** Until the next spell is cast or 24 hours (whichever comes first)

(Boon #7)
**Arcane Shield (Empowered Shield)**
- **Effect:** A protective aura surrounds the caster after casting a spell, granting them a temporary +25 bonus to DB and they take half damage from the next attack made against them.
- **Duration:** 24 hours

(Boon #8)
**Elemental Infusion (Weapon Enhancement)**
- **Effect:** After casting an elemental spell (e.g., fire, lightning, etc.), the spellcaster's weapon (or spellcasting focus) is temporarily infused with that element, dealing an extra critical of the same severity and double damage on their next critical strike.
- **Duration:** Until the next critical strike is delivered or 12 hours (whichever comes first)

(Boon #9)
**Arcane Rejuvenation (Mana Recovery)**
- **Effect:** After casting this spell, the spellcaster regains 1d6 PP then recover expended PP at double the normal rate.
- **Duration:** 24 hours

(Boon #10)
**Arcane Overflow**
- **Effect:** After casting a spell, the caster's magic surges, causing them to regain the PP used to cast this spell and the next lower level spell up to level 5, is free.
- **Duration:** 1 hour

[Malim]

What is this advantage and disadvanteges?

[Druss_the_Legend]

What is this advantage and disadvanteges?

Great question.

Needs testing to have a definite answer but I think it has the following...
Advantages - adds flavour and thematic elements. The blessings could really supe up a spell in interesting ways. It may also open up a design space for casters to get creative with some of their spells because the concept encourages a 'you tell me what the spell does' framework. The Bane effects in a similar way, give the GM some creative license to explain what actually happens when the spell miss-fires.
Disadvantages - its an extra roll or two per spell and cross checking, that could complicate spells just enough to slow down the flow of the game.

[jdale]

I think what you didn't explicitly state is that advantage means "roll twice and pick the better result" and disadvantage means "roll twice and pick the worse result."

[Druss_the_Legend]

I think what you didn't explicitly state is that advantage means "roll twice and pick the better result" and disadvantage means "roll twice and pick the worse result."

Indeed. You sir are 100% correct.