Author: TimFReilly Current version: Milestone 9 Last change: 2022-07-02 22:19:15 Stage: Design

The Curious Reemergence of Castmire

Castmire is a Custom Magic: the Gathering set and setting developed by the Beacon of Creation podcast community. The plane of Castmire is entirely contained in one colossal mansion. All but forgotten to the multiverse for decades, is only now being rediscovered by post-Mending Planeswalkers.

The tone of the plane is "spooky noir" meets "Beauty and the Beast animated furniture" meets "Dungeons & Dragons sprawl". As a set designed with the community, its influences will come from many different people. The conceit of the plane embraces this, encouraging a zoo of creatures and a hoard of items from across the many planes of Magic.

Current Development

Our most recent release is Milestone 9. The set isn't yet full of cards, nor are the mechanics locked down. We playtest every release on Cockatrice. You can find various M8 files here: Milestone Google Drive

Our current release, Milestone 9, contains the work from several focus channels:

  • Some post-M8 changes from the general feedback channel
  • Cards from the "Rhythms of the House" Rare Sorcery Channel
  • Cards from the "What We're Doing with Goblins" Channel
  • A new legend from the "Top Down Costumed Legend" Channel
  • Changes from the "White Visit" Channel
  • A new RW Uncommon from its channel
  • A new blue Legend

We mainly coordinate development and playtests through Beacon of Creation's Discord

Cards that are cut from the set are memorialized in the Room 99 gallery

Ways to Contribute

Set development is guided by design lead Tim, but all card designs come from the community. This means you, too! The simplest way to join the community is to hop on the Beacon of Creation's Discord . Discord is a chat room system similar to IRC or Slack.

In addition to the main #castmire-creations discussion channel, these are the main ways to add your ideas:

  • #castmire-banquet is our free-for-all suggestion box. Pitch any sort of idea there.
  • Design Challenges happen most weeks in conjunction with the podcast. When you submit your idea for a DC, it'll get read on the podcast and may be chosen as a finalist.
  • Focus Channels allow you to contribute to a specific topic, such as a color pair. Here you can help guide a specific archetype with your card ideas and feedback.

Keyword Mechanics

Castmire has three named mechanics.

Visit {cost} (Play this card face down as a land named Unopened Door with "T: Add C." You may turn this card face up by tapping an untapped creature you control and paying this card's visit cost. Visit as a sorcery.)

  • The collapse of the planar portals of Castmire had the side effect of contaminating many of its rooms with the ecosystems of other planes.
  • Explorers of Castmire won't know whether a beautiful Selesyan garden or Atarka's feeding hall will appear behind the next door.
  • All Colors, with "cares about Visit" showing up in Green so far
  • Visit has been very popular so far and is quite promising.
  • While the "untapped creature" and "sorcery speed" parts of Visit are brought up as too complicated, we've seen their use in playtesting. Removing or changing these requirements are on the table, but we haven't locked into anything.

Inhabit ([cost] ([cost]: Exile this card from your graveyard inhabiting target artifact or creature you control as a sorcery. Inhabited permanent gains this card’s abilities.))

  • Castmire is a collapsing artificial plane, in the process of becoming an Entity (as explored in Children of the Nameless novella). It was "programmed" to seek out guests from across the planes, inviting them in one by one and accommodating their needs, but since the Mending you can check out any time you like but you can never leave.
  • Now its gathered memories and the accumulated spiritual residue of past inhabitants result in items taking on life, occasionally helpful to the survivors but increasingly dangerous and unpredictable.
  • Inhabit cards can create crazy combos by stapling new abilities on cards. Inhabit designs focus on quirky abilities.

Investigate (Create a Clue artifact token with "2, Sacrifice this artifact: Draw a card.")

  • Oddities and curiosities abound in Castmire. Can they be touched, broken, and turned into something useful?
  • This mechanic is currently the same as it was in Shadows over Innistrad, with the addition of Eldraine-style Clue cards go to along with the tokens.

Mechanical Themes

Color pair archetypes are evolving over time for the set.

  • WU - Equipment Matters
  • UB - Inhabit Aggro
  • BR - Sacrifice and Goblins
  • RG - Visit Aggro
  • GW - Menagerie
  • WB -
  • BG - Rooms
  • GU -
  • UR - Artifact ETB/LTB
  • RW - Tap/Untap Matters

Experimental Ideas

Castmire also has some unusual cards that represent not-yet-fully-build concepts in the set:

  • Twobrid - Twobrid mana could be helpful to enable decks that play lots of doors. We're still figuring out the exact flavor, but an idea is that twobrid cards are either old or their color is leaking out from them.
  • Spirit Artifact creatures - This is the creature type that conveys an animated object with a personality from some deceased resident of the mansion. This differentiates from a golem or construct since the object wasn't build with animation in mind.
  • Clue cards - Rather than only coming from Investigate, Clues also exist as artifact cards. We have a cycle of "notes", which are artifacts with ETBs flavored as letters or notes. There's also a partial cycle of "murder weapons" from the game/movie Clue/Cluedo.

Setting and Flavor

Haunted Mansion

Castmire was once a bustling plane, serving as a waypoint and trading post for interplanar travel. With the Great Mending, approximately 60 years ago, the plane's portals were severed and the mansion cut off from the multiverse. Those who thought they would only visit the mansion found themselves cut off from their home plane. The state of the mansion initially degraded into chaos, and many of the visitors died or wandered into the endless hallways. In the decades since, though, a peculiar equilibrium has emerged, with some groups settling in and even raising children. Some refuse to settle and instead search for the fabled Exit that will let them go home.

Animated Furniture and Furnishings

The mansion-plane of Castmire is infused with living magic, allowing it to reconstruct and expand itself. Along with that comes a living crew of chairs, tables, rugs, and more. At one time or another, every fixture and fitting has been known to show signs of life, from sconces to tablecloths to loose floorboards. There's speculation as to what intelligence guides these creatures, as they are often seen working together to help clean and repair the rooms.

A Menagerie of Monsters

Even before Castmire was shut off from the rest of the planes, it was known for its zoos of exotic creatures. With the wardens of these places missing or dead, those creatures have been found roaming the rooms. This ecosystem has been further developed by the trapped travelers on Castmire, who have taken to raising and farming creatures from across these planes. The magic of the mansion seems to abide, and entire wings of the building have been transformed to more closely match the planes from which these fauna and flora originate.

Milestone 9

Date: 2022-07-02 22:19:15

Milestone 8 Focus 1 & 2

Date: 2021-09-01 06:10:14

Milestone 7

Date: 2021-06-19 05:23:44

Design Challenges 63 and 64:

Tokens Focus Channel:

Banquet Updates:

Unopened Door now Door:

Signpost Focus Channel

Date: 2021-05-27 05:24:50

Milestone 6

Date: 2021-04-16 22:50:29

Change log:

Milestone 6 Focus Channels

Date: 2021-04-11 22:39:55

Thanks to all the contributors to the Milestone 6 "Fixing" and "Black-Green Rooms" Focus Channels, and special thanks to Dillon and Juliet for leading those channels.

Change log:

Milestone 5 Banquet

Date: 2021-02-03 05:11:41

These are small functionality and formatting updates coming from the Banquet suggestion box.

Change log:

Milestone 5 UR Fix

Date: 2021-01-23 05:39:40

Change log:

Milestone 5

Date: 2021-01-10 02:45:14

RB and UB Focus

Date: 2020-12-20 05:23:58

DC 53 54 55 56

Date: 2020-11-30 00:20:59

UR and RW Focus

Date: 2020-11-24 02:29:36

This update removed the Jumpscare mechanic and adds the new cards from the UR and RW Focus Channels!

Cut cards are memorialized in Room 99:

Change log:

Milestone 3

Date: 2020-07-04 03:35:33

Change log:

Milestone 3 Draft

Date: 2020-07-03 06:59:44

Change log:

CC 39 to 43 DC 39 40

Date: 2020-06-28 01:49:53

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Date: 2020-06-19 07:08:40

CC 34 to 38

Date: 2020-06-12 02:52:15

CC 29 to 33

Date: 2020-05-24 04:08:45

Milestone 2

Date: 2020-04-25 07:20:14

Includes DC33, and CC25-28

Change log:

DC 31 32 CC 23 24

Date: 2020-04-20 05:36:22

M1 Balance 1

Date: 2020-04-12 01:29:42

M1 Flavor

Date: 2020-04-09 05:44:03

Milestone 1

Date: 2020-03-28 05:19:38

CC 19 20

Date: 2020-03-25 18:01:15

DC 25 26

Date: 2020-03-21 23:51:49

Change log:

CC 17 18

Date: 2020-03-17 07:21:15

Change log:

DC 23 24 CC 16

Date: 2020-03-14 21:13:44

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CC 14 15

Date: 2020-03-10 05:54:25

DC 21 22

Date: 2020-03-08 06:33:48

Change log:

CC 11 12 13

Date: 2020-03-06 04:11:49

Change log:

DC 19 20

Date: 2020-03-02 06:22:54

Change log:


Date: 2020-02-25 06:58:45

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Date: 2020-02-17 18:39:04

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Date: 2020-02-11 04:26:07


Date: 2020-02-07 03:58:28


Date: 2020-01-27 06:29:48


Date: 2020-01-14 02:27:37

Change log:

DC 678

Date: 2020-01-07 07:16:22

Change log:


Date: 2019-12-23 06:32:39

Change log:


Date: 2019-12-17 03:37:18

This is the first version of Castmire published on