Homebrew: Mana Points System
Summary
This mana point system is based on the idea that using magic uses your body's mental and physical energy and can cause exhaustion, or even injury, if over-used. All spellcasters have a set pool of Mana Points (MP) that determines how many spells can be cast before incurring penalties.
This system is balanced in a way that allows a spellcaster to cast the same number of spells as they would in the official magic system with no penalties or additional advantages if desired.
Determining a Caster's Mana Points
Total mana points are determined by how many spells per day at each level a character can normally cast under standard rules. The mana points provided are equal to the spell level. Cantrips or 0-level spells do not provide mana. A caster's available mana points are reset under the same conditions as a caster's spells per day in official rules. I.e., a long rest.
Example: A 3rd-level wizard can cast two 1st-level spells and one 2nd-level spell per day. This comes to (2 * 1) + (1 * 2), or 4 mana points.
Cost of Casting Spells
All spells have a base mana cost equal to the spell's level, which is deducted whenever the spell would have counted against the caster's spells per day. It is possible to cast a spell that would cost more mana than a caster has remaining, but doing such incurs penalties. See the Mana Deficits section for details.
For caster classes that use prepared spells, this system only allows a caster to continue using prepared spells at a deficit, and does not allow the casting of unprepared spells.
Any abilities or feats that require spending a spell slot instead spend mana points of the equivalent spell level cost, and incur the same penalties and deficit calculation as a normal spell, unless otherwise listed under Special Considerations.
Mana Deficits
When casting spells, it is possible to gain a deficit (A negative value of remaining mana points). Once a caster has reached a deficit, this represents straining their physical and mental capacity to maintain their magical abilities.
Casting Spells Under a Deficit
If a spell or cantrip is cast while under a deficit, or if casting that spell would place the caster under a deficit, a CON saving throw must be rolled after applying the spell's cost to the deficit, but before applying the spell's actual effects. The DC for this saving throw is equal to 10 + [spell level] + [mana deficit], rounded up. Failing this saving throw incurs a penalty (See Mana Exhaustion). If the caster succeeds the save, the spell is successfully cast.
Example: A caster with -3 mana points wants to cast a 2nd-level spell. They add the spell's level to their deficit, bringing their mana to -5, then roll a CON save against a DC of 17 (10 + 2 + 5).
The following penalties are always applied whenever a caster is under a mana deficit:
- The DC for concentration checks is increased by 1/2 of the mana deficit, rounded up.
- The mana deficit reduces any attack rolls associated with a cast spell. Non-spell attack rolls are unaffected.
- The caster's spell save DC is reduced by 1/2 of the mana deficit, rounded up.
- Damage rolls remain unaffected.
Example: If a caster has -3 mana points and they cast Acid Splash, the caster takes a -3 penalty on the attack roll to hit. The same caster at -3 instead decides to cast Toll The Dead, reducing their save DC by 2 points.
Mana Exhaustion
There are two systems presented for how to handle the penalty additional deficit penalties outside of casting spells. Generally, these only apply if the spellcaster has failed a deficit saving throw.
Exhaustion System
Whenever a caster fails a deficit saving throw, they accrue one point of exhaustion and the associated penalties. This is the recommended option for D&D5e or any other system that implements exhaustion mechanics.
Deficit Penalty System
When under a mana deficit, all ability score, skill check, saving, attack, etc rolls receive a penalty equal to the deficit. This penalty is also applied to saving throws to cast spells under a deficit.
When attempting to cast a spell and failing the deficit saving throw, the caster takes [spell level]d4+[deficit] points of non-lethal damage, and the spell fails but still incurs its mana cost. For cantrips, the damage is 1+[deficit].
Example: A caster with -1 mana points wishes to cast a 2nd-level offensive spell. They first apply the penalties and checks described in Casting Spells Under a Deficit, bringing their mana to -3. If they fail the check, they receive [2d4+3 (8)] non-lethal damage.
Special Considerations
Certain conditions within the core system requires special consideration when implementing the mana points system, such as classes or features. These adjustments are listed below.
D&D 5e - Cleric PHB p56
Channel Divinity: Harness Divine Power TCE p30
You can expend a use of your Channel Divinity to fuel your spells. As a bonus action, you touch your holy symbol, utter a prayer, and regain mana points equal to half your proficiency bonus (rounded up). This feature can be used even when under a mana deficit. The number of times you can use this feature is based on the level you've reached in this class: 2nd level, once; 6th level, twice; and 18th level, thrice. You regain all expended uses when you finish a long rest.
This optional feature for 2nd-level clerics allows you to expend a use of Channel Divinity to regain a spell slot at a level no higher than 1/2 of your proficiency bonus, rounded up. For the purposes of the mana point system, this optional feature will instead allow you to regain mana points eqal to 1/2 of your proficiency bonus, rounded up. The number of uses available per long rest remains the same (Once at 2nd level, twice at 6th level, and thrice at 18th level).
This feature can be used even if the cleric is under a mana deficit.
Example: A 5th level cleric has expended all of her mana points and chooses to use Channel Divinity to regain spell slots. At 5th level, the cleric's proficiency bonus is 3, which allows them to regain 2 mana points.
D&D 5e - Sorcerer PHB p99
Font of Magic - Flexible Casting PHB p99
Creating Mana Points
You can transform unexpended sorcery points into a number of mana points as a bonus action on your turn. The created mana points vanish at the end of a long rest. The table shows the cost of creating mana points of a given amount. You can create up to 5 mana points at a time, but cannot exceed your maximum mana pool.
This ability replaces the Creating Spell Slots ability provided in the Player's Handbook. The mana point exchange is equivalent to the spell slots normally acquired through this ability at the same sorcery point costs, but includes accomodations to prevent players from exceeding their maximum mana pool.
| Mana Points | Sorcery Point Cost |
|---|---|
| 1 | 2 |
| 2 | 3 |
| 3 | 5 |
| 4 | 6 |
| 5 | 7 |
Converting Mana Points to Sorcery Points
As a bonus action on your turn, you can expend mana points and gain a number of sorcery points equal to the number of mana points spent. You cannot use this ability if under a mana deficit, and cannot place yourself under a deficit with this ability.
Exchanging spell slots for sorcery points becomes an easy and simple point exchange. You expend a number of mana points and gain that number of sorcery points. The rules include a clause to prevent entering a deficit to gain more sorcery points.
D&D 5e - Warlock PHB p105
Pact Magic PHB p105
For the purposes of spells gained through the Warlock's Pact Magic ability, all non-cantrip spells are assumed to have a cost of exactly 1 when calculating the Warlock's maximum mana points and the mana point cost of any Pact Magic spell. This is to prevent Warlocks from losing effectiveness when casting spells at a deficit due to increased spell-level cost as the Warlock's Pact Magic grows stronger.
Multi-classing with warlocks will require maintaining a separate mana pool for pact magic spells. The deficits from both your pact magic pool and your other spellcasting pool should be combined for any deficit checks.
Example: A level 5 warlock, under core rules, can cast 2 spells at spell level 3. This provides the Warlock with 2 mana points, and each spell costs 1 mana point, despite their spell level.
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