Thursday, August 13, 2026

Ye Olde Magic

As it is in most fantasy RPGs, magic and spellcasting is a central pillar of the game and the world of CORE20. “Magic Among the Worldborn” in the introduction to the CORE20 Magic Grimoire sets out the broad history of magic and its evolution in Isheridar — the fantasy world that establishes a baseline for the rules of the game. Your CORE20 campaign absolutely doesn’t need to be set in Isheridar (with a number of GMs I’ve talked to running CORE20 campaigns set in the Forgotten Realms and other classic settings). But talking about the relationship between that world and the game’s rules is an effective way of letting GMs and players understand how to adjust that relationship for their own worlds.

A kobold invokes primordial magic to manifest a fire spell as a phoenix ready to attack.

Primordial Power

Primordial arcane power was the first magic wielded by the worldborn, arising among the kobolds in their migrations out of the forbidden dragon heartland of Taliyad more than ten thousand years ago. The origins of primordial magic’s chaotic and destructive power are long lost to time, and are occluded by folk history that almost certainly misstates how the kobolds were granted the mastery of magic by their dragon kin. (Among other things, such lore is contradicted by the fact that dragons have never used primordial magic as far as any histories note.) Still, the magical and elemental fury of the dragons was almost certainly the model that the kobolds sought to mimic when they channeled eldritch power for the first time.

In the lands closest to Taliyad, the oldest tales of kobold witness history record that the first mystics to channel arcane power did so in a legendarily destructive and uncontrolled manner, driven by endless curiosity and a profound lack of self-preservation. Unlike spellcasting’s ordered flow of magic, primordial magic was a personal shaping of magical potential, catalyzing magical effects along the boundary between an invoker’s intent and the raw fury of arcane power. 

Over millennia, the kobolds honed this new art of personal arcane craft, recording it through narrative traditions and stone inscriptions in shrines dedicated to magic. In its earliest forms, primordial magic was an even more chaotic art then the longstanding primordial forms known and learned in the world today. Only a select few were able to fully shape and master the art in the days of the early kobold clans. But over time, the goal of taming the capriciousness of arcane power passed beyond the heroes and warlords who had first mastered its destructive potential, becoming the subject of critical research by kobold scholars and sages. Those who studied primordial magic were the first to understand the broader potential of arcane power — and it was through them that the channeling of magic spread to the folk of other lineages.

The Old Arcana

As it’s presented in the game, primordial magic is the oldest form of arcane magic, predating the spellcasting traditions that have long since supplanted it. Primordial magic is a personal magic, shaped and honed by intent and necessity in ways beyond the rigid forms that spellcasting allows. But within the game, primordial magic is defined in terms of spellcasting, with the rules effectively reversing the relationship between primordial magic and spellcasting to make primordial magic as easy to play as possible.

Primordial magic is modeled very much after the first presentation of the warlock in D&D, from 3rd edition’s Complete Arcane — the first D&D book I ever worked on as an editor (though the warlock class wasn’t one of my sections). Primordial magic is manifested as invocations — magical features that resemble the spells they evolved into, but whose casting is more fluid and more flexible.

Altering Invocations

Invocations respond to your will as a caster, and are channeled as unique representations of your magic. Historically, spells are the fixed representation of primordial magic that was once more freeform and personalized. As such, you alter your invocations by changing the mechanics of the spells you use as a baseline for those invocations, in ways that a spellcaster can’t. 

A primordial caster in CORE20 has the freedom to shape their invocations in many ways. They can alter the presentation of their magic, deciding whether an obscuring mist effect takes the form of swirling fog, clinging shadow, or a swarm of intangible insects. Casters can alter the range of their invocations at the expense of strength, creating a fireball at twice the distance by imposing disadvantage on the challenge throw that sets the save DC. They can increase the duration of their magic by dampening its effect, or can heighten effects by shortening duration. They can expand the number of creatures targeted by their magic by spreading out a slightly weakened effect over more targets.

You can check out the full scope of the rules for primordial magic in chapter 10 of the CORE20 Player’s Guide, or in a four-page PDF sample.

Building an Invoker

For simplicity’s sake, chapter 1 (“Building Your Character”) of the CORE20 Players’ Guide focuses on traditional spellcasting. The “Spellcasting Options” in the “Feat Packages” section don’t present an option for primordial magic — but you can use the following custom feat package and fast-start suggestions if you want to get your invocations on.

Primordial Caster

6 Feat Slots

You are a practitioner of a form of arcane magic older than spells and magic items alike. As a channeler of primordial magic, you harness raw arcane power, shaping it to your will and intent. Take this feat package if you wish to make use of arcane spells with your own distinct flourishes. You’ll benefit the most from this feat package if Intelligence (the spellcasting ability for a primordial caster) is one of your best ability scores.

Eldritch Spirit (arcane) ×1: You channel the power of arcane magic.

Primordial Caster ×1: You can channel arcane magic in its primordial form. You gain a number cantrip invocations equal to your Intelligence modifier, based on any arcane cantrip.

Invocation Mastery ×3: You are caster level 3, granting you three invocations based on any arcane spells of 3rd level or lower. You can manifest those invocations up to three times per day (or a number of times equal to your Intelligence modifier if it’s higher than 3).

Arcane Blood ×1: You negate the penalty to your critical points imposed by Invocation Mastery.

Fast-Start: Invocations

To quickly build a primordial caster character, you can select starting invocations and cantrip invocations reflecting common and useful spells. The CORE20 Magic Grimoire has full information on these spells.

The cost is broken out for each level of invocation, which comes out of your 150 gp starting wealth. You know a number of cantrip invocations equal to your Intelligence modifier. You know a number of higher-level invocations equal to your caster level, which can reflect any spells of your caster level or lower.

Primordial Invocation Package

This package contains the following invocations and cantrip invocations, reflecting the spells of the same name:

0 level (5 gp each): Detect magic, eldritch blast, mage touch, touch of fatigue

1st level (7 gp each): Mage armor, mesmerism, shadow shroud

2nd level (12 gp each): Blighted claws, harrowing retreat

3rd level (25 gp each): Blade storm, energy resistance

Art by Vagelio Kaliva


Thursday, July 23, 2026

Torment Temple

Torment Temple is a new adventure for the CORE20 public playtest, designed for tier 1 characters (including starting characters)!

An ancient relic. An even more ancient curse. An undead-haunted ruin to which that relic must be returned before it’s too late.

(It’s funnier than it sounds.)

The cover of the “Torment Temple” adventure. The cover art features a zombie dressed in rags reaching out toward the viewer, their expression feral and their mouth open in a snarling scream.

Standing in the midst of idyllic farmlands, the ruins known as Torment Temple have been shunned by locals for nearly two decades. Known as Torman’s Temple before that time, the site was home to a monastic order named for a holy warrior of the pre-Imperial age. Legends tell how the temple was raised over a site marked by an evil curse that had long despoiled nearby lands, and how the presence of Torman’s order caused that curse to fade away. But when an earthquake leveled the temple 18 years ago, the curse transformed the ruins into a place of undead risen from the temple’s faithful, and who dwell there still in a corrupted mockery of cloistered life.

Mercenary adventurers exploring the site in the early years declared it infested with zombies and sparse on loot. Locals now give the ruins a wide berth, marking the forest around the site with warning signs. But a month ago, a necromancer seeking treasure of a different kind arrived at the site, laid claim to it — and dispensed with the minor artifact that had quietly been keeping the worst effects of the ancient curse at bay.

• • •

Torment Temple is available for free download in the “Starter Adventures” folder in the CORE20 playtest folder on Google Drive. Or click on the “CORE20 Playtest” page link above for more information on the CORE20 RPG.

Tuesday, May 26, 2026

A Life Well-Lived: Backgrounds in CORE20

Character backgrounds have been around in d20 fantasy games since before the phrase “d20 fantasy games” existed — but not always under that name. The concept of a background was known as “player character non-professional skills” way back in AD&D. These were a list of semi-medieval vocations your character might have picked up before their adventuring career took off, and which encouraged a DM to “adjudicate situations in which these skills are used or useful.”

D&D 3rd edition talked about background in a narrative sense, class by class, but focused on its newly minted skills system to cover any and all ideas of what your character might have been good at before taking up the call to adventure. For 5e D&D, backgrounds became a distinct mechanic focusing primarily on narrative, splitting the focus between a character’s former vocation (with backgrounds such as acolyte, sage, and sailor) and life experience (charlatan, hermit, and outlander, among others). 

As a system built around the idea of rules modularity and flexibility, CORE20 takes a slightly different approach. Backgrounds in CORE20 are all about life experience, and are intentionally broad in flavor and limited in scope so as to make them easy to fit to and personalize for any character concept.

An adventurer in black leather armor and a dark cloak stands in a snowy forest, a sword at her side and a crow perched on her hand.

Where Do You Come From?

As the CORE20 Player’s Guide puts it:

Your character’s background helps to define their life up to the point when they took up the path of adventure. Just as all characters have unique perspectives and traits defined by their lineage, all characters have a particular upbringing that shaped them in important ways. But where your character’s lineage helps to define their broader relationship to the world and its history, your background has a more direct connection to childhood, home, and family — whether your character carries the memories of those things dearly, or has walked away from the past with no desire to turn back.

Background Versus Vocation

The idea of past professions and vocations that can tie into a character’s adventuring lifestyle are also front-and-center in CORE20 — but are handled through the use of customized personal skill groups. Just as your character might invest feat slots in the Athletics, Magic, or Thievery skill groups to represent focus and training useful for an adventuring lifestyle, you can also take feat slots in a personal skill group, covering anything from Scout to Goat Rancher to Standup Comedian (all personal skill groups that have made an appearance in my CORE20 campaigns).

As part of their background, all CORE20 characters gain a +3 bonus that can be spread across one or more personal skill groups of a player’s choice, so that you don’t need to worry about downplaying skill groups useful for adventuring just for the sake of a more flavorful personal skill group. But you can likewise use feat slots earned during the campaign to improve your character’s prowess with personal skill groups, building a character whose past vocations continue to serve them.

A Range of Backgrounds

From the Player’s Guide again:

Nine different backgrounds cover the broad strokes of the experiences that have shaped your character — criminal, exile, gentry, magical, military, outlander, rural, wanderer, and urban. Your character’s background might be a strong match to their chosen path in life, with the benefits of a chosen background providing a foundation of knowledge and training. For example, many martial-focused characters choose the military background, and the magical background is a good fit for any spellcaster. 

Alternatively, part of the richness of your character’s story might come from the juxtaposition between the life they once lived and the life they choose now. A character with the outlander or rural background brings a unique perspective to a city campaign, just as a character who grew up in the city or among the gentry does in a dungeon. And backgrounds such as exile and wanderer can provide any character with an intrinsic sense of seeking something, which the campaign can ultimately provide.

Criminal

Take this background for any character with a shady past — or who plans to have a shady future.

Exile

This background suits any character who has turned away from their homeland or past, whether by choice or by necessity.

Gentry

This background is appropriate for any character who grew up in relative luxury, whether they’ve turned their back on that lifestyle or continue to flaunt it.

Magical

This background suits any character with a backstory tied to spellcasting, magical crafting, or magic-related lore.

Military

Take this background for any character who has spent time in proximity to organized battle.

Outlander

This background fits any character with an affinity for the wilderness.

Rural

Take this background for any character at home in villages and remote settlements.

Urban

Take this background for any character at home in the city.

Wanderer

This background reflects a life spent on the move, whether as a part of nomadic life or from a simple case of wanderlust.

The Way of the Wanderer

The wanderer background covers a lot of territory (pun intended) as far as the many types of adventuring characters who might make use of it — a former mercenary sellsword, a mage who spent years investigating sites of magical power, a con artist keeping one step ahead of the law, and more.

Each background comes with a range of unique benefits, and you can choose whichever one of those benefits feels like the best fit for your character. Working with the GM, you can also develop an alternative benefit that fits your character concept, and whose value is in line with the benefits presented here.

The wanderer background from the CORE20 Player’s Guide.

Universal Benefits

In addition to the unique benefits broken out for each background, taking a background provides a number of universal benefits at character creation.

Ability Score Increase

The life your character has lived (especially the early formative years) helps to shape their physical and mental prowess. When you choose your background, you can raise one of your ability scores by 2, or raise two of your ability scores by 1 each. Each background comes with suggestions for which ability scores to raise, but you can choose whatever ability scores reflect your character’s chosen path and training.

Skill Affinity

A character’s background provides an aptitude for particular skills. At character creation, a character gains a +3 bonus that can be applied to a number of favored skill groups for that background. A character can take a +3 bonus to one skill group, take a +2 bonus to one skill group and a +1 to a second group, or take a +1 bonus to three skill groups, as the player decides.

All backgrounds also grant a character a +3 bonus to checks with any personal skill groups. These personal skill groups reflect the vocations, hobbies, and interests that are a part of every character’s life, and will often connect to the character’s backstory or environment.

Default Languages

By default, all characters can read, write, and speak or sign a regional language (typically tied to the area in which they have lived the longest or the most recently). Characters can also learn the spoken Imperial language or Imperial Sign — the twinned trade languages that became the universal lexicon of the Empire, and which are still used in most areas of the world. Characters of all lineages except human also know a spoken or signed lineage language tied to their lineage’s history.

As part of their background, your character gains three bonus feat slots to take the Learn Language feat three times — for a regional language, Imperial, and a lineage language.

Art by Vagelio Kaliva.

Thursday, January 29, 2026

More Playtest Monsters

As of right now, the v1.1 update to the CORE20 Playtest Creature Package is live for your gaming pleasure! As always, you can find the new document and all the other v1.1 playtest docs in the CORE Playtest Files folder on Google Drive: 

http://tinyurl.com/CORE20Playtest

(If the short URL doesn’t work for you, you can click or copy the full link here.)

A red dragon, as seen on the cover of the CORE20 Playtest Creature Package.

The initial v1.0 Playtest Package featured a solid array of over 180 creature stat blocks from d20 fantasy, covering potential foes, foils, enemies, and allies for your CORE20 games. The v1.1 package ups the monstrous ante to over 240 stat blocks with the addition of 54 new creatures, including:

  • Bulette
  • Grick
  • Hippogriff
  • Ilvalaak — a new name for the naga
  • Kraal — inspired by the grell
  • Krenshar
  • Werebear
  • Mesmeroth — a renamed and reworked gibbering mouther
  • Oni
  • Peryton
  • Praetyrian and venenatus — two new drakes
  • Remorhaz
  • Revenant
  • Satyr
  • The skulker — a revisiting and combining of the classic AD&D monsters the trapper and the lurker below
  • Specter
  • Transfixer — the piercer, but really cool
  • Vampire spawn
  • Vargouille
  • Vermacarn — a reworked carrion crawler
  • Vocoeur — CORE20’s version of the displacer beast
  • Wurfrur — the renamed blink dog
  • Xorn
  • Lineage traits for the gnoll and the mergyyr (a new name for the merfolk), allowing the easy creation of a broad range of NPCs

And many more!

In addition to new threats and allies, the Playtest Creature Package has seen all manner of updates, tweaks, corrections, and rules and language fixes. Huge thanks as always to all the folks in the playtest who have pointed out typos and asked the questions that have let us make the game even better. (The Playtest v1.1 Changelog doc in the playtest folder notes changes to existing stat blocks and lists the playtest package’s new creatures.)  

Once again, the CORE20 Playtest Creature Package is available in two variations. The regular version features the stat block color-coding throughout all sections of the stat block, while the “(Low Color)” version features the color coding only on stat block section heads. (A post back toward the beginning of the public playtest talks about the evolution and design of the stat block format, including using color to make it easier to navigate stat blocks during play.)

I’ve been playtesting and fine-tuning all these new creatures in my own campaigns for a while now, and I’m happy to finally turn them loose. Good gaming!

Art by Xavier Beaudlet

Wednesday, January 14, 2026

Creature Preview: Mesmeroth

A gibbering mouther by any other name would… well, still be pretty horrible. But the renaming of this classic weird fantasy aberration was a relatively late addition to CORE20, in the course of my learning that ableist language is something that too easily hides within familiar usage.

The gibbering mouther was so-named for the endless maws that would appear across their amoeboid form, and for the confusion-inducing gibbering of the voices that would issue forth from those many mouths. Terrifying heroes since the early days of AD&D, the mouther had always seemed a classic aberrant creature to me, possessed of an alien intelligence whose very language would tear at the minds of those who heard it.

Except then during a round of sensitivity consulting for the CORE20 public playtest, I was asked, “You do know that ‘gibber’ and ‘gibbering’ likely originated as a description of the speech of the mentally ill, right?” And I said, “Uh… no…” — even as I realized I probably should have. I definitely wish it was something I’d known when I was the editor of the 5e D&D Monster Manual in 2014, so that there might have been a conversation on the topic at the time. Not that it likely would have made any difference, as D&D is a large ship that changes course very slowly when it comes to dealing with making little fixes. Thankfully, though, CORE20 is a bit more nimble in its desire to improve the language and context of the game.

Before the release of the public playtest of CORE20, the gibbering mouther became the mesmeric mouther for a time. It’s now become the more subtly named mesmeroth in the upcoming public playtest CORE20 Playtest Creature Package v1.1. The mesmeroth for our game is built on the chassis of the SRD mouther, but monster developer Aaron Gray has swapped out the traditional confusion effect of their many voices for a luring drone that draws adventurers ever-closer to their doom.

(Click on the stat block header below to download the full stat block in PDF.)

The header info for the mesmeroth stat block.


Friday, January 2, 2026

Creature Preview: Gnoll

The gnoll has always been one of my favorite humanoids, back from the days when “humanoid” was a dirty word in D&D, used exclusively to describe the evil, monstrous folk designed to antagonize the humans and demi-humans (elves, dwarves, and the like) who were the heroes of the game. D&D has always had a consistently one-note version of who gnolls are and how they live, building on the evil pack hunters of AD&D and 3e, to 5e’s fiend-spawned humanoids/actual fiends. But in keeping with the central tenet of CORE20, it felt like gnolls in our game would be most interesting if they can be anything they — and you — want.

It’s easy to focus on the gnoll as a feral hunter, and to create a stat block that builds them out around that single theme. But as with the worldborn lineages in CORE20 (the game’s name for D&D’s humanoids), the cultures of the more unusual — and often magically evolved — wondrous worldborn are meant to cover the broadest possible range of characters and types. As such, the upcoming update to the CORE20 Playtest Creature Package sets up the gnoll as a lineage trait stat block, giving them the same treatment as humans, elves, dwarves, orcs, goblins, and the rest of the worldborn lines. 

As with worldborn NPCs, the gnoll’s lineage traits can be added to any of the game’s twelve nonplayer character stat blocks, creating gnoll-themed scouts, warriors, and wildlings who’ll feel at home alongside any previous versions of the gnoll. But you can also use the flavor and culture of the gnoll to lend a distinct shape to spellcasters, protectors, scoundrels, and more. 

Additionally, it’s easy to see how the stat block lineage traits for the twelve worldborn lineages in the Playtest Creature Package have been adapted straight from the player character traits in chapter 4 of the CORE20 Player’s Guide. So it’s an easy guess that these gnoll lineage traits have been created with an eye to a future project — setting up character traits that will allow players to create wondrous worldborn characters in addition to the baseline worldborn options. More info on that as it comes together.

(Click on the stat block header below to download the full stat block in PDF.)

The header for the gnoll lineage traits stat block.


Wednesday, December 17, 2025

Creature Preview: Bulette

The bulette is a delightful monster whose name I definitely pronounce as “bull-EHT,” not “boo-LAY” as some do. (I have been known to joke that the creature is only pronounced “boolay” if it comes from the Boolay region of Greyhawk. Otherwise, it’s just sparkling landshark.)

The bulette for CORE20 maintains much of the feel of the D&D original. As a tier 3 creature, it makes an excellent solo threat against a tier 1 or tier 2 party, built for power and jumping, and with a prodigious ability to flatten foes. In a recent encounter, I was able to happily confirm that this design had its intended effect when, after watching a bulette break the ground with a surging leap, then drop onto a pack of miniature mammoths they were hunting, the player characters elected to all flee the scene at high speed.

(Click on the stat block header below to download the full stat block in PDF.)




Ye Olde Magic

As it is in most fantasy RPGs, magic and spellcasting is a central pillar of the game and the world of CORE20. “Magic Among the Worldborn” i...