MRC Design Notes

Mercurial Heart launches on May 17th, 2024! It is an expansion set that supports all seven classes, and the advanced elements found in Azoth (astra, neos, and umbra). In this article, we’ll be covering the new strategies players can explore found in MRC, as well as its accompanying Re:Collection decks.

Silvie Re:Collection, Slime Sovereign

Re:Collection decks are opportunities for us to further explore the champions from previous sets, as well as the worlds they come from. As such, Silvie, Slime Sovereign is from Cambria!

Slimes of All Colors

In this deck, Silvie gets obsessed with befriending slimes! This very colorful archetype allows you to have access to all elements of Slimes, thanks to Spirit of Slime, and Silvie, Slime Sovereign.

Baby Slimes

Baby slimes are great for building early board presence. Each baby slime is an animal, which means there is no pride requirement needed for obedience.

Food Items

Despite their cute presentation, these snacks provide a nice bonus to any slimes that you play. These slime nourishing snacks provide a boost to your early game plays, making your Baby Slimes and basic element slimes that much sweeter to play.

Advanced Element Slimes

The advanced element slimes finally reveal themselves and loan Silvie their power! This set of Slimes showcase each of the unique themes of Crux, Luxem, Arcane, and Tera. They are meant to be late game powerhouses that Silvie can utilize to reclaim dominance of the board.

Tristan Re:Collection, Shadowdancer

Tristan returns in Azoth! From the shadows, the new Umbra Assassin is now here! The new Tristans Lv. 1 and 2 open up a new way to play the early game of assassin while Tristan, Shadowdancer gracefully utilizes the power that the Umbra element offers.

Tristan reappears in Azoth!

With the new Tristan Re:Collection deck, we delve further into the ideas of swiftness and versatility associated with the Assassin class. Thus, introducing the new agility keyword. If you gain agility, you will return an amount of cards back from your memory to your hand at the beginning of that turn’s end phase.

Note: Multiple instances of agility trigger at the beginning of the end phase. You may choose the cards you return to your hand from your memory.

Ominous Shadows

Introducing the first new phantasia ally in the game, Ominous Shadows are a key part to Tristan’s late game strategy. The Ominous Shadows provide both offense and defense capability to Tristan, but require careful planning to use.

One Step Ahead

Careful planning should be rewarded accordingly! These new additions synergize really well with agility and reward you for holding up interaction.

Playing the Long Game

New preparation generators provide easier access to early game plays, or inversely try saving as many preparation counters as possible for big late game turns!

Umbra Utility and Finishers

These new Umbra Cards show the versatility that Umbra has to offer, and those that are unprepared to face off against it approach imminent doom.

Mercurial Heart First Edition

Now that we’ve covered the Re:Collection decks, let’s cover the cards from the main booster box, Mercurial Heart first edition!


Imbue provides a new way to activate cards in Mercurial Heart! By reserving the cards needed to play a card with the imbue keyword revealed, you gain additional effects as long as the elements of all the cards revealed and the card activated match! (Revealed cards are hidden again after costs are paid.)

Note: These cards are revealed as you reserve them into your memory, thus don’t enter the state of being hidden and revealed. So “whenever you reveal this card from your memory” triggers do not work with Imbue. Imbue rewards deckbuilding by choosing to include more cards of the same element to gain bonus effects.

Automatons & Powercells

Automatons become a major archetype in Mercurial Heart! Automatons make use of the new Powercells to amplify their damage and provide some burst damage to the ally archetype.

Increasing Danger

Added fuel to the flame, in Mercurial Heart the stakes are higher, but those who can manage the risk will be able to reap the rewards. Added self-damage effects make fire riskier to play, but the added bonus is sure to make you think twice.

Into the Depths

The tide brings in bountiful rewards for those who are able to capitalize on it. In Mercurial Heart, water gets added support for the self-mill theme by introducing more ways to get cards into your graveyard and utilizing those resources once they’re there as well.

A Perfect Breeze

The winds of change bring new ways to interact and provide useful tools to those who embrace it. Wind gains more versatility in Mercurial Heart by adding more unique interactions for those that wish to be prepared for any situations that may arise.

Advanced Elements

Mercurial Heart also brings added support to our Trio featured in Alchemical Revolution! New advanced element cards have been added for each archetype and expand on the strategies found in the previous set.

Shiny Cards

We are bringing back the CUR (Collector’s Ultra Rare)! Previously only found in Dawn of Ashes first edition booster boxes, CURs are serialized and uniquely stamped versions of some of the most desired Grand Archive cards. The CSRs and the CUR found in Mercurial Heart first edition booster box are exclusive to this first edition printing.

This concludes the design notes for Mercurial Heart! Re:Collection and Mercurial Heart was really fun for us to design and test. We hope you have a great time with the new additions to the game and are looking forward to seeing everyone collect/play with the new cards at our future events!

Print Run

  • Mercurial Heart First Edition Booster Boxes - 27,750 boxes (not reprintable)
  • Tristan Re:Collection, Shadowdancer - 6,000 collections (reprintable)
  • Silvie Re:Collection, Slime Sovereign - 6,000 collections (reprintable)

  • For more information about the release of Mercurial Heart first edition and the Re:Collection decks, check out the product sheet here:

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