How Spellcasting Monsters Work in the New Monster Manual

Casting Monsters Are Now Spell Slot-Less

Spellcasting monsters in the 2025 Monster Manual have shifted away from the traditional spell slot system toward a more streamlined approach. This change is aimed at making encounters faster and ensuring that Dungeon Masters can run powerful spellcasters smoothly without juggling complex spell lists. The new design is particularly evident in powerfully magical creatures like the Lich, which we’ll use as an example of how these changes have manifested.

The Old vs. New Approach

Previously, spellcasting monsters functioned like player characters with spell slots and an expansive list of prepared spells. While this system offered versatility, it also required a lot of bookkeeping. The updated design replaces the spell slot mechanic with something more akin to Innate Spellcasting (which has previously been seen as a monster trait in 5e).

In this new system, monsters have access to a certain number of spells, and they can cast each a set number of times per day.

Let’s take a closer look at how this affects the 2025 Lich.

The New Lich: A Streamlined Spellcaster

Instead of getting the same spellcasting as a level 18 Wizard with daily spell slots, the new Lich has a list of spells it can cast at will, twice per day, or once per day.

Here’s what changed:

• At-Will Spells: The Lich can freely cast utility spells like Detect Magic, Detect Thoughts, Dispel Magic, and some offensive spells like Fireball (at level 5) and Lightning Bolt (at level 5).
• Limited Use Spells: It can cast Animate Dead, Dimension Door, and Plane Shift twice per day.
• Powerful Daily Spells: Its most devastating abilities, Chain Lightning, Finger of Death, Power Word Kill, and powerful utility spells, like Scrying, are each available once per day.
• Reactions for Defense: The Lich still can cast Reaction-based spells, like Counterspell or Shield normally, but they are located in the Reactions section of the stat block.
• Spell Attacks: It also has Eldritch Burst, which can be either a Melee or Ranged attack, as a default option in their Mulitattack. They can opt to use this in combination with their good ol’ Paralyzing Touch to output damage instead of casting a spell as a Magic action.

How Has Globalized Innate Spellcasting Changed the 5e Landscape?

With innate spellcasting now serving as the default for spellcasting monsters, 5e has shifted away from creatures functioning like PCs and toward a more predictable, thematic playstyle. While this change removes some flexibility, it ensures that spellcasters always have access to their most important spells.

This change also allows monsters to user multiple spells and spell-like abilities in a single turn. In the 2024 Player’s Handbook, the rule for multi-spell turns has been changed so that you cannot cast a spell by expending a spell slot more than once per turn. Seeing as monsters don’t have spell slots, they can use spell-like actions and Bonus Actions without running into this rule.

Less Varied But Streamlined Combat

One of the biggest impacts of this change is that spellcasting monsters now have a more focused combat role. Gone are the days when a DM had to decide whether a creature should use their last level 3 spell slot to cast Counterspell. Instead, monsters are designed with pre-selected abilities that reflect their intended combat role. This means:

• Less cognitive load for DMs: No need to track slots or weigh complex spell options.
• More efficient action economy: Monsters can use Bonus Action and Reaction-based spells without sacrificing their main action spell resources.

Bonus Actions and Reactions Spells Are Easier to Use

A major benefit of the new system is that Bonus Action and Reaction-based spells are now baked into a monster’s mechanics. In older editions, a DM might forget that a creature had Shield or Counterspell available due to the complexity of tracking spell slots.

They may also run out of spell slots and be unable to use these spells once they get deeper into a drawn out encounter.

Now, these abilities are simply listed under the creature’s Bonus Actions and Reactions, ensuring they can get used every turn

Spell-Like Effects Can Stifle Counterspelling PCs

Spell-like effects, like the Lich’s Paralyzing Touch or Eldrtich Burst, aren’t spells, they are spell-like effects. This helps with consistency but has the side effect of making Counterspell less effective because Counterspell only works when a creature casts a spell using Verbal, Somatic, or Material components.

What This Means for Other Spellcasters

The Lich is just one example of this broader change. Other spellcasters in 5e, from Mind Flayers to Yuogloths (and now dragons!), have followed a similar model. This shift ensures that powerful enemies retain their magical prowess without requiring extensive prep and tracking work from the DM.

For DMs, this means encounters will run faster, and for players, it means they’ll see monsters using their most thematic spells  but may have more predictable “video game-esque” turns. The days of a spellcasting monster running out of useful spells mid-fight—or a DM forgetting half its spell list—are gone!