THE UNDERREALM FIELD GUIDE

Shroom and Gloom Builds

Build around what your cards actually do. Start with a plan for damage and a plan for recovery.

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

Grow a reliable attack

The official game description confirms that even starting cards can be grown and modified. As an editorial starting point, choose an attack you can use consistently and evaluate upgrades around that plan.

Look for
Growth conditions you can actually trigger with your current deck.
Potential advantage
A clear purpose for your upgrade choices.
Trade-off to check
Can you still handle a hand that does not contain the upgraded attack?
Use this approach when
Your deck already supports the card’s condition, without relying on an unverified combo.
Understand card growth →
02 / RECOVERY PLAN

Make food part of the plan

Eating enemies for health and using roasted enemies in soups are officially described mechanics. Assess recovery alongside attacks when you choose cards.

Look for
Cards in your actual hand that produce or use food.
Potential advantage
A plan for sustaining health through a run.
Trade-off to check
Does preparing recovery prevent you from dealing with the current threat?
Use this approach when
Your current card text supports the food interaction you intend to use.
Understand eating →

Check a combo before committing

  1. Read the trigger. Make sure you understand what must happen before the effect resolves.
  2. Count the required resources. Use current in-game costs, including any modifications.
  3. Check the target. The launch update distinguishes single enemies, multiple enemies and player buffs.
  4. Consider the fallback. Decide what you will do if one part of the combination is unavailable.

What about character builds?

Each launch character starts with distinct decks and a base Foresight. Those differences matter when evaluating a plan, but this edition does not yet have verified starting lists or tested character-specific builds. Start with the confirmed roster.

Are there any verified “best builds”?

Not in this edition. No complete build has been tested here in the current Early Access version. The transcript-based patterns below are starting points for experimentation, not verified rankings or matchup guarantees.

Pattern: give growth cards the finishing blow

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

The first supplied playthrough uses Hungry Blade as a kill-based growth attack. The transferable idea is to feed a reliable finisher, rather than distribute every kill without a plan.

  • Setup: use other attacks to put an enemy within the finisher’s current damage range.
  • Payoff: land the finishing hit with the growth card when the incoming damage makes that safe.
  • Failure case: delaying a kill for growth may cost more health than the upgrade is worth. A deck also needs a plan for turns when the finisher is not drawn.

Prioritize enough usable attacks to control the fight. Add draw or upgrades to support an existing plan, rather than depending on a future reward to make it function.

Pattern: connect food production to eating rewards

The supplied run links Roast-generated food with effects triggered by eating, including Toothpick generation and growth on Scavenger Blade. This is a transcript-reported interaction, not a tested current-version deck list.

  1. Establish a dependable way to produce food.
  2. Check the eating payoff and whether it is active when you consume that food.
  3. Count energy and draw as well as damage: extra cards do little if you cannot play them.
  4. Keep enough recovery to survive a hand that does not assemble the loop.

Food can also have exploration uses. If your hand allows feeding a creature or trading with a merchant, compare that opportunity with immediate healing. Do not assume every merchant takes food.

Pattern: support Machines with Data and cleaning

The Facility playthrough combines Machine cards with Data activations and Gunk removal. Think of these as separate jobs: a useful effect to trigger, a way to trigger it, and enough affordable plays to keep the turn moving.

  • Machine support: the transcript shows Employee Handbook triggering a turret. Check that the Machine is an eligible target and that repeating its effect addresses the current enemies.
  • Cleaning support: the player uses Sweep on a Gunk-covered card before playing it. Inspect whether cleaning first improves your actual hand or consumes a resource you need elsewhere.
  • Fallback: avoid a hand full of activation cards with no Machine available, or expensive Gunk payoffs with no way to clean them.

Start from the cards already working together. The source does not establish an optimal ratio, an infinite loop or a universal best Facility build.