New Feat/magic system: Arcane Reserves

[Mr0wlington]

This variant can be used as either a feat, or just a way to extend the way magic works in your campaign. It's designed to emulate the way magic works in certain fictions by allowing the spell caster to gain levels of exhaustion in exchange for extra spell slots. If you want to use this as just a variant instead of a feat, just remove the Con bonus and requirement to take it as a feat!

Feat: Arcane Reserves
You defy the laws of magic to cast more spells than seem physically and mentally possible, sacrificing your body to the magic.

• +1 to your constitution score, up to a maximum of 20.
• You may regain, and immediately use a spell slot that you have expended. You can regain a slot equal to the spell slot level - Con bonus (a negative score will increase the cost of the slot). After the spell is cast, immediately take (level of spell slot - Con modifier) levels of exhaustion. (Minimum of 1 level of fatigue).
• The exhaustion is magical in nature, and can only be healed through natural means.
• It is possible to kill yourself through exhaustion with this ability. If this happens, your spell goes off before you die.

C&C more than welcome. It's worded slightly differently than my original reddit post, but please let me know what you think!
(also, this is my first ENWorld post, long time lurker!)

 

[Dragongrief]

Welcome to active life on the boards. I like the flavor, and it would provide an interesting option for spellcasters. I can see it having much more effect in campaigns where downtime is more available vs. constant dungeon delving.

The biggest balance concern I can see is this:

You may regain, and immediately use a spell slot that you have expended. You can regain a slot equal to the spell slot level - Con bonus (a negative score will increase the cost of the slot). After the spell is cast, immediately take (level of spell slot - Con modifier) levels of exhaustion.

As written, there is no limit to the number of spells you can cast, as long as your Con Mod is high enough (Con 20 = unlimited 5th level and lower spells). It could easily be limited by making is "X/day" or "minimum 1 level of exhaustion." Other than that, it would just be determining whether the spell was worth the exhaustion level.

 

[Mr0wlington]

Oh yeah! That 1level minimum was supposed to be there!
Thanks for the catch!

 

[Mr0wlington]

Does anyone think that the caster should possibly need to succeed on a concentration check to do this?

 

[Khaalis]

First, welcome to the boards!

Now secondly, sorry...
I'm not so sure I like the instant burn out facet of this ability. 5E usually doesn't lean that heavy.

Another way to do this is use a mechanic already in the game that accomplishes something similar. The only difference is that you have to cast first, then gain the extra spell power and fatigue. Fictionally it might be described - "when drawing the magical energy for the spell you wish to cast, you overdraw on the magical power to hold for use casting another spell."

Also, since you state "immediately" this indicates a mater of time (i.e. not something really done in "downtime"), so you need to indicate what time unit. As you have it written I'd go with Action or maybe Bonus Action. I might also lower the severity of the exhaustion acquisition. It seems like on one hand you want the ability to be usable more than one, on the other you want it to be a 1 use and burn-out type of ability.

In this version I propose, it already limits the maximum regenerated spell slot to 4th level, is limited as a diminishing return if you are on your last spell slot (e.g. you have 1 5th-level slot left and use this to gain a 4th, then a 3rd, a 2nd and a 1st). Fatigue acts as the final limiter against burning through a bunch of say 2nd level spells. The maximum uses is obviously 6. If you push that far, its safe to assume you're pretty much dead anyway. I also have No problem with the use of magic to reduce exhaustion since the only two spells that I can see that do it are Greater Restoration (5th level) and Wish (9th).

Thus, this is how I'd present it.

Arcane Reserves
Prerequisite: The ability to cast at least one spell.
Your drive overrides most caster's limits of spellcasting, allowing you to push yourself physically and mentally farther than most, sacrificing your body to channel more magical energy.

• Your Constitution increases by 1, to a maximum of 20.
• When you cast a spell of 2nd level or higher using a spell slot, you can immediately regain one expended spell slot. The slot must be of a level lower than the spell you cast and can't be higher than 5th level. As soon as the expended spell slot is refreshed in this manner, take 1 level of Exhaustion (PHB p291).