THE UNDERREALM FIELD GUIDE

Shroom and Gloom Mechanics

Know what the mechanic does before spending your next card.

Game version: Early Access / Sources checked: September 11, 2026

Combat Deck & Explore Deck

Combat cards handle battles. Explore cards help you navigate dungeons, modify cards and unlock new abilities.

How it works

The official description presents two distinct decks with different jobs. Think about which part of the run a card helps when making a selection.

Example

An exploration choice that modifies an attack can support your future combat plan. This is a conceptual example, not a named recipe.

Common mistake

Evaluating every card only by immediate combat damage.

Card growth

Cards can grow and be modified. Their initial form is not necessarily their final form.

How it works

The Steam description confirms growth for both low-level starting cards and rare cards. The exact upgrade rules depend on the card; this guide does not assign a universal growth rate.

Example

When comparing your upgraded attack with a screenshot, compare the full text instead of assuming that a matching name means matching damage.

Common mistake

Treating one screenshot’s numbers as a permanent database value.

Eating & healing

Enemies can become recovery: the game supports eating them for health and using roasted enemies in soups.

How it works

This is confirmed by the official gameplay description. Exact healing, preparation requirements and soup effects must be read from your current cards.

Example

Before spending a food card, compare the recovery it offers now with the other uses your current hand explicitly allows.

Common mistake

Assuming every food restores the same amount or follows a recipe from an older build.

Foresight

Each launch character has a base Foresight card that changes how they play.

How it works

This is confirmed in the Early Access launch announcement. It also confirms character-specific starting decks. Read the base Foresight alongside those cards when learning a character.

Example

Before building around a trigger, check the Foresight shown for the character you selected.

Common mistake

Assuming Demo reward counts, passive lists or carry-over rules are verified for Early Access. Exact current Foresight effects and unlock rules are not yet verified here.

Rest, Warmth & Threat

Adapted from gameplay transcripts; check current card and room rules. Transcript sources ↓

Treat exploration Rest as a resource refresh with a room-dependent risk, rather than a guaranteed heal.

Across the supplied playthroughs, players rest to regain energy and cycle exploration cards. The review describes increasing danger as they remain in a room; warmth can offset danger, while environmental warnings can add hazards. The useful number is the consequence currently displayed by your game, not a damage formula copied from a video.

Before you rest

  1. Have a reason to stay. Name the tool or resource you need: a dig, an unlock, a reveal or a way to use a structure.
  2. Check the warning again. Look for predicted damage and objects that change when you rest. Do not assume that the previous turn’s safe state still applies.
  3. Use relevant protection first. If a card can add warmth or address the displayed hazard, check its target and cost before refreshing your hand.
  4. Keep an exit plan. Compare the possible reward with the health and tools needed to reach the next encounter.

One other transcript uses “Rest” for a healing card. Its effect text does not establish what the exploration Rest action does. Current damage scaling and all hazard interactions remain untested here.

Fatal, Consume, Exhaust & Linger

These distinctions are consistently useful when reading the supplied gameplay transcripts. The current in-game tooltip takes priority over the transcript’s wording.

  • Fatal: a bonus tied to a killing hit. Lowering a target’s health and then using the intended finisher can change what you gain from the same fight.
  • Consume: described as destroying the card after use. It does not by itself mean that the card is food or heals you.
  • Exhaust: described as removing a card for the encounter, rather than permanently deleting it from the run.
  • Linger: described as keeping a card in hand at the end of the turn. This can help preserve one part of a combination while waiting for another.

Also inspect limited-use counters. A battery charge, a consumable tool and an exhausted card have different implications for later encounters.

Gunk, Data & Machines

The Facility transcript describes Gunk increasing the cost of affected cards. The player uses cleaning effects on cards in hand to reduce that burden. Some effects also benefit from adding or removing Gunk, so cleaning everything immediately is not always the intended sequence.

In the same run, Data activates a targeted Machine card. Read both halves: what produces the Data, and what the selected Machine does when triggered. A machine that attacks a random enemy does not become a precise finisher just because you can trigger it again.

Before taking another Machine, check whether the deck has enough activation and draw to use it. Before taking a Gunk payoff, check whether the increased cost leaves the hand playable. See the Facility build checklist.

Automatic saves

The launch announcement says the game saves after you win a fight or escape a dungeon.

Common mistake

Assuming an arbitrary mid-fight exit preserves that exact moment. The announcement does not make that guarantee.