This chapter is your workshop. It covers encounter design, enemy types, zones and terrain, non-combat challenges, and session pacing. By the end, you'll have every tool you need to run compelling sessions of Halcyon Aces.
Designing Encounters
Encounter design in Halcyon Aces revolves around two axes: the three-action economy and zone-based positioning. A good encounter isn't "four enemies in a room." It's a tactical situation where terrain matters, focus fire is dangerous, and the party's deck resources are under pressure.
Step 1: Start with the Space
Before you pick enemies, sketch the zones. A fight's terrain does more to shape its tactics than any stat block. Ask yourself: how many zones? What makes each one different? Where do the players enter? What can change during the fight?
A typical combat space has 3-5 zones. Fewer feels cramped (everyone's in melee immediately). More can dilute the action (too much Striding, not enough fighting). Three zones is the sweet spot for fast, focused fights. Five zones suits complex encounters with ranged enemies, terrain objectives, or multi-front battles.
The party needs to storm a watchtower held by bandits. The GM sketches four zones:
- Approach (open ground, no cover - dangerous for the party)
- Tower Base (cover from rubble, +2 Guard vs. ranged attacks from above)
- Tower Interior (tight space, only 2 characters can be Engaged per side)
- Tower Top (Elevated Terrain, +1 EV on ranged attacks downward)
The bandits have two melee fighters at the Tower Base and an archer on the Tower Top. The party starts in the Approach. Immediately, the space creates decisions: rush across open ground to the base? Return fire from the Approach? Split up to flank? The zones do the work.
Step 2: Set the Action Budget
Each combatant gets actions per turn: 3 for PCs and most Elites, 2 for Minions, 4 for Bosses (plus Legendary Actions). The total enemy actions per round is your encounter's action budgetâit determines difficulty more reliably than any single stat.
| Encounter Difficulty | Enemy Actions/Round | Description |
|---|---|---|
| Easy | 6-8 | Low pressure, resource drain |
| Standard | 9-12 | Balanced challenge |
| Hard | 13-16 | Real threat, high resource cost |
| Deadly | 17+ | Climactic encounters only |
Note: For a party of 4 PCs (12 actions/round). Adjust by roughly 3 actions per additional PC.
The key insight is that action economy matters more than raw stats. Six Minions with 2 actions each (12 total) are often more dangerous than two Elites with 3 actions each (6 total), because the Minions flood the field, force the party to split attention, and can focus fire on a single target.
Step 3: Choose Enemies
Pick a combination of enemy types that creates the tactical dynamic you want:
- Horde fights: 5-8 Minions. Fast, chaotic, action-economy pressure. The party burns through cards mowing down fodder, which is the pointâyou're spending their deck, not challenging their builds. Good for early-session encounters that thin resources.
- Focused fights: 1-2 Elites, possibly with 2-3 Minion support. The Elite is the real threat; the Minions create flanking pressure and prevent the party from focusing fire. This is the bread-and-butter encounter.
- Boss fights: 1 Boss with phases, Legendary Actions, and possibly Minion waves. The centerpiece of a session or arc.
- Mixed threats: Different enemy types that demand different responses. An Elite melee fighter plus a ranged Minion pack plus an environmental hazard. The party can't solve everything with one approach.
Step 4: Add a Twist
The difference between a good encounter and a great one is usually a single complication that changes the party's calculus. Some ideas:
- A countdown. The bridge is collapsing in 4 rounds. The hostage is being dragged away. The ritual completes in 5 rounds unless the caster is stopped. Countdowns force aggressive play and punish over-caution.
- A secondary objective. Protect a civilian. Keep the alarm bell from being rung. Recover the artifact before it falls into the pit. Splitting focus between combat and objectives creates agonizing decisions.
- Reinforcements. More enemies arrive on round 3. Or an ally arrives on round 4. The fight's dynamics shift mid-combat, forcing the party to adapt.
- Changing terrain. The floor starts collapsing zone by zone. The room floods. A fire spreads. When the ground literally shifts beneath you, no plan survives.
Building Enemy Stat Blocks
Enemies in Halcyon Aces use simplified stat blocks. They have the same four stats as PCs but don't need a full Trait/Perk/Talent breakdown. Instead, they get a short list of abilities that define their tactical role. The goal is fast resolution at the table: a GM should be able to run an enemy by glancing at a stat block, not studying a character sheet.
Enemy Types
Minions
Expendable. Low stats, low Vitality, down in 1-2 hits. They exist to create pressure through numbers, burn PC actions, and make the party's deck thinner.
- Actions/Turn: 2
- Card Method: Fixed value (typically 6-8). No draw, no deck, no decision.
- Purpose: Fast to run, fast to die. Create action economy pressure.
Elites
Real threats. Stats comparable to PCs, proper Techniques, and they draw from the GM's deck. An Elite should feel like fighting another player characterâdangerous, unpredictable, and capable of critical hits.
- Actions/Turn: 3
- Card Method: GM deck draw. The GM draws from a shared 52-card deck, choosing cards just like a PC. The GM's deck thins over the encounter. Resonance works normally.
- Purpose: Challenging opponents that demand tactical play.
Bosses
Set-piece encounters. High stats, deep Vitality, multiple combat phases, and Legendary Actions that fire between PC turns. A Boss anchors a climactic encounter and demands coordination.
- Actions/Turn: 4 (plus Legendary Actions)
- Card Method: GM deck draw + floor. Draws from the GM deck, but effective value can never go below a set floor (usually 8-9). If the drawn result would be lower, it becomes the floor value instead.
- Purpose: Climactic encounters that test everything the party has learned.
The GM uses a single standard 52-card deck for all Elites and Bosses in an encounter. When multiple Elites are active, they all draw from the same pool. This means a prolonged fight exhausts the GM's deck tooâcreating a tension curve that mirrors the PCs' experience.
For Boss encounters, consider giving the Boss its own dedicated deck to prevent an early-fight Elite phase from depleting the Boss's resources. The GM's deck is also public information. Players can see the GM's fatigue pile and count remaining cards. Smart players will track thisâand that's great. Tactical awareness is part of the game.
Legendary Actions
Bosses get Legendary Actionsâspecial actions that fire between PC turns. A Boss typically gets 2-3 per round. After any PC's turn ends (but not during it), the Boss may use one. Each specific Legendary Action can only be used once per round.
Design Principles
Good Legendary Actions create pressure without removing player agency. They should disrupt plans, not obliterate them.
- Movement is always safe. A Legendary Action that repositions the Boss 1 zone is useful and never feels unfair. It forces the party to adjust, but doesn't deal damage or inflict status effects.
- Single-target attacks are fine. One attack against one target keeps pressure on without wiping the party. Keep damage moderateâLegendary Actions should sting, not devastate.
- Avoid hard crowd control. A Legendary Action that Stuns the whole party is miserable. Keep status effects single-target or use weaker debuffs like Weakened or Rooted.
- Summoning is powerful. Dropping a Minion or two via Legendary Action refills the action budget and forces the party to split focus. Use this when you want to escalate.
Legendary Action Rules
- A Boss's Legendary Actions are listed on its stat block.
- After any PC's turn ends, the Boss may use one Legendary Action.
- Each specific Legendary Action can only be used once per round.
- Legendary Actions refresh at the start of the Boss's turn.
- Legendary Actions do not cost the Boss's normal 4 actions.
Multi-Phase Boss Encounters
The best Boss fights evolve. When a Boss reaches a Vitality threshold, its stat block changes: new abilities unlock, old ones may be replaced, the arena may transform, and the narrative escalates. This is a phase transition, and it should be the most dramatic moment in the encounter.
| Phase | Vitality Threshold | Description |
|---|---|---|
| Phase 1 | Full Vitality | The learning phase. The party figures out the Boss's patterns, identifies vulnerabilities, and develops a strategy. The Boss fights at its baselineâdangerous but predictable. |
| Phase 2 | ~50% Vitality | The adaptation phase. The Boss changes tactics: it becomes faster, more desperate, or reveals a hidden power. The arena might changeâa floor collapses, reinforcements arrive, a hazard activates. The party's Phase 1 strategy may no longer work. |
| Phase 3 | ~25% Vitality (optional) | The final stand. The Boss goes all-in with its most dangerous abilities. This phase should feel climacticâvictory is close, but the threat is at its peak. A desperate enemy is a dangerous enemy. |
Phase Transition Rules
- When a Boss reaches a phase threshold, the transition triggers immediatelyâeven if it's not the Boss's turn.
- Any abilities marked as "Phase 1 only" are lost. New abilities from the next phase become immediately available.
- The Boss's Guard, Resolve, or Legendary Actions may change between phases.
- Narrate the transition dramatically. Describe what the players see: armor cracking away to reveal something underneath, the arena shaking, the Boss's voice changing, fire erupting from new sources. Phase transitions are the Boss fight's act breaksâmake them feel like it.
Environmental Hazards & Terrain
Terrain transforms a fight from a stat-check exchange into a tactical puzzle. Every zone in a combat encounter should have at least one interesting featureâsomething to stand behind, climb on, avoid, or exploit. If every zone is identical flat ground, positioning doesn't matter, and that wastes one of the system's core strengths.
| Terrain Type | Effect | Examples |
|---|---|---|
| Difficult Terrain | Stride costs 2 actions instead of 1. | Rubble, thick mud, dense brush, icy floor. |
| Hazardous Terrain | Creatures entering or starting their turn here take damage (1-3). | Lava cracks, toxic gas, thorn thickets, live wires. |
| Concealment | Attacks into or out of this zone suffer -2 EV. | Dense fog, smoke, heavy rain, magical darkness. |
| Elevated Terrain | +1 EV on ranged attacks from here. Melee from below: -1 EV. | Rooftop, balcony, cliff ledge, rampart. |
| Cover | +2 Guard against ranged attacks while in this zone. | Stone walls, barricades, overturned carts. |
| Burning Zone | 2 damage + Burning on entry or start of turn. | Spilled oil, wildfire, magma flow. |
| Collapsing | Body DC 10 at end of each round or fall to a lower zone, taking 3 damage. | Crumbling bridge, unstable floor, sinking ship. |
Non-Combat Challenges
Not every challenge is a fight. Social encounters, exploration puzzles, and narrative crises use the same core resolutionâdraw, play, compareâbut require different framing from the GM. The card system handles these beautifully if you set the right stakes and give each stat a way to contribute.
Social Encounters
Social encounters work best when they have structure: a goal, an obstacle, and a failure state. "Convince the magistrate to help" is a goal. "She's suspicious of outsiders" is an obstacle. "If you fail, she sends you away and you lose your only lead" is a failure state.
For simple negotiations, use a single opposed check: the PC's Heart vs. the NPC's Mind (or Heart vs. Heart for an empathetic plea, Mind vs. Mind for a logical argument). For complex social encounters, use an extended check with a progress threshold.
The party needs the Warlord's army to march south. The Warlord is proud, pragmatic, and unimpressed by outsiders. The GM sets this as an extended check:
- Progress Threshold: 12
- DC: 10
- Round Limit: 4 (the Warlord's patience)
Each round, one or more PCs can attempt to persuade, with the stat depending on their approach:
- Heart: Impassioned speech, appeal to honor
- Mind: Strategic argument, proof of mutual benefit
- Body: Physical demonstration of strength (the Warlord respects warriors)
- Spirit: Invoking a prophecy or divine mandate the Warlord believes in
Exploration Challenges
Exploration challenges use a mix of individual checks, group checks, and extended checks. The goal is varietyârotate between stats so that every party member gets a moment to contribute.
A dungeon delve should test:
- Body: Climbing, swimming, forcing doors
- Mind: Spotting traps, recalling lore, navigating
- Heart: Calming frightened NPCs, resisting despair
- Spirit: Sensing magic, communicating with spirits, detecting hidden enchantments
Pacing a Session
Halcyon Aces' fatigue system self-regulates pacing, but the GM still controls the overall rhythm. Here are the principles that make sessions feel right:
The Three-Encounter Arc
Most sessions work well with 2-3 meaningful encounters (combat, social, or exploration) separated by rest opportunities:
- The first encounter establishes the threat and starts thinning decks.
- The second raises the stakesâdecks are thinner, Vitality may be dented.
- The third is the climax, where every card matters.
Breather Placement
- A Breather between encounters 1 and 2 restores decks but not Vitality. This creates the feeling of "we're sharp but battered"âmechanically fresh, narratively wounded.
- A Short Rest before the climax restores half the deck and some health. Enough to fight, not enough to feel safe.
Deny the Full Rest
If the party can Full Rest after every encounter, the fatigue system collapses and tension evaporates. Full Rests should require narrative commitment: a safe location, 6+ hours, and acceptance that the world moves while they sleep. The enemy advances. The hostage suffers another day. The ritual draws closer to completion. Make the time spent have consequences.
Let the Deck Tell the Story
When a player's fatigue pile is visibly thick and their deck is thin, that's tension the system created for you. Don't undercut it with easy outs. Don't offer surprise rest opportunities unless the narrative demands it. Let the squeeze happen. That's where the best table moments live: the healer with 12 cards left, choosing between a Healing Touch and saving cards for the boss room.
Session: The party descends into the Ember Vault.
- Encounter 1 (Social): Gathering information in Cindermaw. Light card usageâmaybe 4-6 cards per player on social checks. No rest needed.
- Encounter 2 (Exploration): Navigating the Vault's corridors. Moderate card usageâ8-12 cards per player across group checks and extended checks. Some Vitality lost to hazards. The party takes a Breather at a safe chamber (decks restored, Vitality stays damaged).
- Encounter 3 (Boss Fight): The Ember Warden. Heavy card usageâ15-25 cards per player across 4-6 rounds. Techniques, Active Guard, initiative, Strikes. By round 4, decks are thin and every play is agonizing.
Total cards spent: roughly 27-43 per player across the session. No character hits deck exhaustion, but everyone feels the squeeze by the boss fight. That's the target.
Ready to populate your encounters? Check out the Bestiary for complete enemy stat blocks across all tiers. Want to run your first session? The Starter Scenario provides a complete introductory adventure with pre-generated characters.