I'm interested in devising a homebrew system for spellcasting beyond one's regular capabilities. Will this description be unambiguous and keep relative power balance between non-casters, third-casters, half-casters, and full-casters?

Likewise, are there any ways to mechanically exploit this system, and are there any revisions that allow for greater clarity of the system itself?


If in dire need, any spellcaster is capable of expending their own life force to enhance their connection to the Weave. This allows them to cast one prepared spell without consuming a spell slot.

When you do so, you must make a DC 10 + Spell Level Constitution Saving Throw. On a failure, you take a number of levels of exhaustion equal to the spell's level immediately after the spell is cast. On a success, you take a number of levels of exhaustion equal to half of the spell's level, rounded up, immediately after the spell is cast. If the saving throw is failed by 5 or more, you take the levels of exhaustion immediately and the spell fails to cast.

You can only Overcast spells at a Spell Level less than or equal to your highest level spell slot plus one, the total of which is no higher than nine.

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    – Someone_Evil
    Dec 9, 2019 at 22:07
  • 2
    \$\begingroup\$ Is it intended that failing the save on a 6th or higher level spell is instantly fatal? \$\endgroup\$ Dec 9, 2019 at 22:10
  • \$\begingroup\$ Yes, the goal is that casting something that powerful without a spell slot is supposed to be incredibly dangerous to the caster - even to the point of death \$\endgroup\$ Dec 9, 2019 at 22:15
  • \$\begingroup\$ Why does the limitation on spell slot level have "plus one"? If my highest slot is 5, I can't prepare 6th level spells to begin with, can I? \$\endgroup\$
    – GreySage
    Dec 9, 2019 at 22:15
  • \$\begingroup\$ No, but if you have a spell that can be level cast (such as magic missile), then you can increase the level to spell level six. However, since many spells aren't defined for 10th level spellcasting, that exception had to be made. \$\endgroup\$ Dec 9, 2019 at 22:19

1 Answer 1


Will this [...] keep relative power balance between non-casters, third-casters, half-casters, and full-casters?

By definition, no—you are giving an extra feature to spellcasters, that you aren’t giving to non-casters. So, almost tautologically, this feature shifts balance in casters’ favor.

  • \$\begingroup\$ That is true, though when I say "relative power balance" I just ask whether it makes casters significantly more powerful than non-casters, as opposed to asking whether it makes casters at all more powerful than non-casters. Perhaps I'll revise the post to make this more apparent. \$\endgroup\$ Dec 9, 2019 at 23:03
  • \$\begingroup\$ @GuardsmanJon You’re going to have to define “relative power balance” pretty rigorously. For instance, the general consensus is that spellcasters are already—typically—quite a bit stronger than noncasters are. This is “significant” in the statistical sense of being a real phenomenon and not just the result of random noise. So if things are already somewhat skewed in casters’ favor, and we know this is going to lean further in their favor, how on earth can we know when it’s “too much”—or even quantify how much it is? \$\endgroup\$
    – KRyan
    Dec 9, 2019 at 23:06
  • \$\begingroup\$ True, though some (including myself) would argue that while it is technically an increase in power just as any increase in freedom is an increase in power, this creates a greater potential for self-sacrifice of casters in the same way that front-line fighters practice self-sacrifice. Because the option exists, there may be an expectation for them to act on it. If they act on it because of this, they face dangerous consequences they wouldn't otherwise agree to. Killing casters isn't the goal of this, but the inherent role shift this offers undermines the idea that they only benefit from this. \$\endgroup\$ Dec 9, 2019 at 23:24
  • \$\begingroup\$ @GuardsmanJon That analysis is flawed because the caster is in complete control over whether they use it or not. “Someone might make a mistake and use it at the wrong time” is not really a balancing factor. \$\endgroup\$
    – KRyan
    Dec 9, 2019 at 23:45
  • \$\begingroup\$ Just as a cleric is in full control of when they heal. They are, but they're still shunned if they act solely on self-interest \$\endgroup\$ Dec 9, 2019 at 23:48

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