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Some monsters, like a lich, have the Spellcasting trait. This trait allows such monsters to cast spells using spell slots, much as spellcaster player characters do.

However, taking the lich as an example, the trait does not mention how spell slots are regained (I'm ignoring their Lair Actions for the purposes of this question). Looking at the general rules on monsters' Spellcasting trait in the Special Traits section:

A monster with the Spellcasting class feature has a spellcaster level and spell slots, which it uses to cast its spells of 1st level and higher. The spellcaster level is also used for any cantrips included in the feature.

The monster has a list of spells known or prepared from a specific class. The list might also include spells from a feature in that class, such as the Divine Domain feature of the cleric or the Druid Circle feature of the druid. The monster is considered a member of that class when attuning to or using a magic item that requires membership in the class or access to its spell list.

A monster can cast a spell from its list at a higher level if it has the spell slot to do so. For example, a drow mage with the 3rd-level lightning bolt spell can cast it as a 5th-level spell by using one of its 5th-level spell slots.

You can change the spells that a monster knows or has prepared, replacing any spell on its spell list with a spell of the same level and from the same class list. If you do so, you might cause the monster to be a greater or lesser threat than suggested by its challenge rating.

There is no mention of spells slots coming back on a long rest. Elsewhere in the general rules, this is explicitly mentioned for other traits (such as X/Day traits):

For example, "1/Day" means a special ability can be used once and that the monster must finish a long rest to use it again.

It's reasonable to assume that monsters with the Spellcasting trait do probably get their spell slots back on a long rest because that's how it works for PCs, but on the other hand, monsters and PCs don't necessarily use the same rules. So, does anything explicitly state that monsters with the Spellcasting trait get their spell slots back on a long rest?

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Spell slots recover on a long rest

The rules have a parenthetical supporting this

The spellcasting rule for monsters states the following (Monster Manual, p. 10; emphasis mine):

[...] A monster with the Spellcasting class feature has a spellcaster level and spell slots, which it uses to cast its spells of 1st level and higher (as explained in the Player's Handbook). [...]

It seems that this all-important parenthetical is not found on D&D Beyond's version of the Basic Rules, but a similar one can be found on page 113 of the actual Basic Rules document. I cannot assume anything but that the parenthetical missing is a mistake. Thus we can conclude that monsters follow the same spellcasting rules as characters meaning that the rules on "Spell Slots" (found in the PHB) apply. Those rules state:

[...] Finishing a long rest restores any expended spell slots. [...]


Below is my answer before the parenthetical was pointed out, it provides a way to conclude the same, even without the parenthetical. The rule is found in the Player's Handbook and yet it applies to monsters as well; here are two reasons:

Other rules in the same location apply to monsters

Say we decided that that rule is in the PHB and thus does not apply to monsters. Also in the PHB, in the same chapter in fact, are the rules on areas of effect, the rules that define what a cone, cube, cylinder, line, and sphere are. These rules clearly apply to monster abilities, so I believe the rule that spell slots recover on long rests should as well.


The Variant Spell Points rule provides some evidence

The "Variant: Spell Points" rule states, in part (DMG, p. 288):

In this variant, each spell has a point cost based on its level. [...]

[...] you regain all spent spell points when you finish a long rest. [...]

[...] This system can be applied to monsters that cast spells using spell slots, but it isn't recommended that you do so. Tracking spell point expenditures for a monster can be a hassle. [...]

Seeing as how this system of spell use can be applied to monsters and would have them recover their spell points after a long rest, it should similarly be the case that monsters can recover their spell slots after a long rest.

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  • 1
    \$\begingroup\$ Nice reasoning. +1 \$\endgroup\$ – KorvinStarmast Jun 28 at 19:25
  • \$\begingroup\$ MM P10 points to the PHB section on spell slots as well. \$\endgroup\$ – Slagmoth Jun 29 at 0:41
  • \$\begingroup\$ @Medix2: There's a similar parenthetical in the basic rules PDF, just not on the DDB version of the monsters chapter of the basic rules for whatever reason: "[...] which it uses to cast its spells of 1st level and higher (as explained in chapter 10 of this document)." (I've pointed this discrepancy out on DDB's Discord.) \$\endgroup\$ – V2Blast Jul 11 at 23:44
  • \$\begingroup\$ Well done, +1. BTW one unimportant nit-pick of terminology: the form of argument you made that you called "evidence by contradiction" is called, in the art, reductio ad absurdum (reduction to absurdity). You demonstrated it nicely: If we assumed that rules for spells in PHB can't apply to monsters, then rules for cone, line etc. would not apply, which is absurd. Thus that assumption is absurd. QED. Perfectly valid reductio. \$\endgroup\$ – Valley Lad Jul 13 at 0:57
  • \$\begingroup\$ @ValleyLad Ah yeah that's fair. I was definitely going for the usual sense of contradiction where the assumption monster attacks have shapes is proven wrong if we assume the rule on spell slots doesn't apply monsters. I cleaned up the wording a bit, hopefully fixed that \$\endgroup\$ – Medix2 Jul 13 at 1:52

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