Gaming Rules-design note One Hero Engine

One Hero Engine: Magic

The current spellcasting draft for One Hero Engine, including MP rules, casting paths, provisional spell lists, and mythic spells.

Spellcasting

  • MP = 5 + your casting stat modifier.
  • Spell Save TN = caster’s full stat score (target’s saving throw).

Confirmed casting procedure

The current v0.12 draft consistently supports the following spellcasting loop:

  1. Choose a spell.
  2. Pay its MP cost.
  3. If the spell calls for a saving throw, the target rolls a saving throw against the caster’s Spell Save TN.
  4. If the spell gives a direct effect, range, duration, or damage step, use that spell text.

The current draft does not define a universal casting roll, a universal failed-casting rule, or a universal spell-attack rule outside specific spell text.

Rules review required: The current source material does not define this procedure consistently.

MP recovery

At the start of each new day (after an 8-hour long rest), a character automatically recovers 1d4 MP. This represents the natural replenishment of magical energy through rest and focus.

HP-to-MP conversion

During a short rest or as a free action, you may choose to sacrifice a portion of your HP to recover additional MP. Use the conversion:

  • For every 2 HP sacrificed, you recover 1 MP.

This optional sacrifice must be used judiciously during encounters when extra MP is needed, balancing the immediate cost of HP loss against the benefit of increased magical capability.

Casting paths

  • Ash-Binder: +1 MP, always roll 1 Risk Die.
  • Veilwalker: 1/day ignore a failed spell.
  • Whisperbound: +1 die, take 1 HP.
  • Runesmith: Store 1 spell in an item (1/day).

Concentration, duration, and summoning

The current published draft only references concentration explicitly in individual spell text such as Grave Hunger. It does not define a universal concentration subsystem.

The draft also uses summoning effects in individual spells such as Bone Golem and Raise Dead, but it does not define a separate global minion or summoning procedure outside those spell entries.

Rules review required: The current source material does not define this procedure consistently.

Spells (Ideas)

This table lists 50 spells available in One Hero Engine. The Paths column indicates which archetypes or class concepts can adopt the spell (e.g., Arcane for general magic, Necromancer for dark/death magic, Veilwalker for illusions/shadow, Whisperbound for mind/forbidden lore, and a composite group for Cleric/Paladin/Monk/Ranger). MP costs, ranges, and effects are intended as guidelines and may be adjusted to fit your campaign.

NameMP CostRangeEffectPaths (Example Archetypes)
Arcane Grasp230 ftTelekinetically pull or push the target; target must succeed on a STR save to resist.Arcane, Ranger
Arcane Lance260 ft (line)Fires a line attack that deals Step 3 damage.Arcane, Paladin
Arcane Recall2SelfRecovers a just-cast spell (usable once per session).Whisperbound, Arcane
Arcane Shield1SelfGrants +1 Soak until your next turn.Arcane, Cleric, Paladin
Bless (entry A)230 ftBestows a +1 bonus on allied rolls for 3 rounds.Cleric, Paladin, Monk
Blur1SelfForces attackers to roll with Disadvantage until your next turn.Veilwalker, Monk
Bone Armor1SelfGrants +1 Soak for 3 rounds. Cannot be cast if you are wearing physical armor or if another defensive (armor) spell is active.Necromancer, Paladin, Cleric
Bone Golem430 ftSummons a large undead ally (2 HD, deals Step 3 damage) for 1 scene.Necromancer, Cleric
Bless (entry B)230 ftGrants Advantage on self or allies’ rolls for 3 roundsCleric, Paladin, Monk
Counterspell230 ftCancels an enemy spell (check vs. the caster’s stat).Arcane, Cleric
Cloak of Silence1Self/AreaMutes all sound in a 10 ft radius for 1 minute.Veilwalker, Ranger
Compel Truth230 ftForces target to answer truthfully (target must pass a WIS save, or the effect applies).Whisperbound, Cleric
Dazzling Veil130 ft coneBlinds enemies in a cone for 1 round (target must pass a WIS save).Veilwalker, Ranger
Deathgate360 ftOpens a portal to summon skeletal arms; restrains target (target must pass a STR save).Necromancer, Cleric
Death Whispers160 ftFrightens the target (target must pass a WIS save to avoid panic).Necromancer, Whisperbound
Detect Magic130 ftReveals magical auras around objects and creatures.Arcane, Ranger, Cleric
Divine Light130 ftDeals Step 2 radiant damage and slightly heals nearby allies.Cleric, Paladin, Ranger
Drain Life230 ftDeals Step 2 damage and heals you for an amount proportional to the damage dealt.Necromancer, Cleric
Dream Echo2TouchImplants a false memory; the target is confused for 1 round.Veilwalker, Whisperbound
Eldritch Bolt260 ftDeals Step 3 psychic damage.Whisperbound, Arcane
Eye of the Void2SelfGrants vision of invisible or magical auras for 1 minute.Whisperbound, Arcane, Ranger
Forbidden Words1SelfEnhances the next spell’s Target Number by +1, making it harder for targets to resist.Whisperbound, Cleric
Ghoul Claws2MeleeDeals Step 3 damage; target must succeed on a save or be paralyzed for 1 round.Necromancer
Grave Hunger230 ftSummons spectral jaws dealing Step 2 damage per round (requires concentration).Necromancer
Healing Word130 ftRestores 1d4 plus stat bonus HP to one ally.Cleric, Paladin
Invisibility3TouchGrants invisibility for 1 minute, or until you attack.Arcane, Veilwalker
Lightning Ray260 ftFires a ray that deals Step 3 damage and may arc to a second target.Arcane, Paladin
Life Ward2SelfAbsorbs up to 1d6 damage for a short duration.Cleric, Paladin
Mage Step110 ftTeleports you to a visible point.Arcane, Veilwalker, Ranger
Magic Missile160 ftAutomatically hits and deals Step 2 damage.Arcane, Paladin, Ranger
Mental Probe130 ftReads surface thoughts; deeper insight requires a WIS save.Whisperbound, Arcane
Mirror Image2SelfCreates 2 illusory duplicates that can confuse attackers.Veilwalker, Arcane
Mind Shatter360 ftDeals Step 4 psychic damage and stuns the target on a failed save.Whisperbound, Necromancer
Phantom Blade2MeleeDeals Step 3 damage; bypasses some armor bonuses.Veilwalker, Arcane, Paladin
Primal Roar230 ftForces enemies within 10 ft to make a fear check (WIS save required).Ranger, Paladin
Radiant Burst330 ft radiusDeals Step 3 radiant damage to all enemies within the area.Cleric, Paladin, Ranger
Raise Dead210 ftAnimates an undead minion (1 HD, 1 HP); lasts 1 scene.Necromancer, Cleric, Paladin
Sacred Barrier2SelfGrants +3 Soak for 1 minute.Cleric, Paladin
Smite2MeleeDeals extra radiant damage (Step 3) and forces a saving throw.Paladin, Cleric
Soul Leech330 ftDeals Step 2 damage; if target dies, you regain 1 MP.Whisperbound, Necromancer
Spell Echo3SelfRecasts your last spell at -1 MP cost (usable once per scene).Arcane, Whisperbound
Spirit Sense1SelfDetects nearby undead and lingering souls.Necromancer, Cleric
Shadow Grasp260 ftDeals Step 2 damage and restrains the target (target must pass a STR save).Veilwalker, Necromancer
Shadowstep130 ftTeleports you between shadows.Veilwalker, Arcane
Thought Thief230 ftSteals a spell from the target (they lose it for 1 hour; target must pass an INT save to resist).Whisperbound, Necromancer
Tranquil Mind1SelfReduces incoming damage by 1 Step for 1 round.Monk, Ranger
Umbral Chains360 ftBinds up to 3 enemies; targets must pass a WIS save to escape.Veilwalker, Necromancer, Ranger
Whispering Madness230 ftConfuses the target for 1 round (target must pass a WIS save).Whisperbound

Rules review required: The current published v0.12 source contains two different published Bless entries with conflicting effects. They are preserved above as separate draft entries because the repository does not provide a newer authoritative correction.

Draft spell-design ideas

The following notes are preserved as published design ideas rather than confirmed core spellcasting rules:

To add depth and strategic flexibility during casting, consider these options for “overcharging” spells:

  • Overcharge for Increased Damage: Spend 1 extra MP on a damage spell (e.g., Magic Missile) to upgrade its damage one Step higher than normal.
  • Extended Duration: For buff or defensive spells (like Arcane Shield or Sacred Barrier), spending an extra MP increases the duration by one round.
  • Widened Area: For spells with an area effect (e.g., Radiant Burst or Nature’s Wrath), an additional MP cost may expand the area of effect or allow the spell to affect an extra target.
  • Chain Casting: Some spells (such as Spell Echo or Arcane Recall) can be boosted by extra MP to allow immediate recast or restoration of another cast spell during the same turn.
  • Enhanced Save Difficulty: For spells imposing conditions (like Mind Shatter or Forbidden Words), spending extra MP can force targets to suffer a harsher penalty on their saving throws.

These MP boost options add a layer of resource management and tactical choice, letting players decide when it is worth sacrificing extra MP for an amplified effect.

Use this spells table and MP boosting ideas to create a rich and varied magical repertoire for your One Hero Engine games, tailoring spell choices to your character’s flavor and the challenges of your story.

Mythic Spells

  • Use once per session.
  • Cost: 3+ MP. Always succeeds (no roll).

Examples:

  • Chronoseal - Take 2 turns in a row.
  • Ashgate - Open a portal.
  • Wound the World - Corrupt a location.

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