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.

Archived version: One Hero Engine v0.12 is an archived development draft. It is preserved for design history and is no longer the current rules version.

Return to the current One Hero Engine rules.

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.

Name MP Cost Range Effect Paths (Example Archetypes)
Arcane Grasp 2 30 ft Telekinetically pull or push the target; target must succeed on a STR save to resist. Arcane, Ranger
Arcane Lance 2 60 ft (line) Fires a line attack that deals Step 3 damage. Arcane, Paladin
Arcane Recall 2 Self Recovers a just-cast spell (usable once per session). Whisperbound, Arcane
Arcane Shield 1 Self Grants +1 Soak until your next turn. Arcane, Cleric, Paladin
Bless (entry A) 2 30 ft Bestows a +1 bonus on allied rolls for 3 rounds. Cleric, Paladin, Monk
Blur 1 Self Forces attackers to roll with Disadvantage until your next turn. Veilwalker, Monk
Bone Armor 1 Self Grants +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 Golem 4 30 ft Summons a large undead ally (2 HD, deals Step 3 damage) for 1 scene. Necromancer, Cleric
Bless (entry B) 2 30 ft Grants Advantage on self or allies’ rolls for 3 rounds Cleric, Paladin, Monk
Counterspell 2 30 ft Cancels an enemy spell (check vs. the caster’s stat). Arcane, Cleric
Cloak of Silence 1 Self/Area Mutes all sound in a 10 ft radius for 1 minute. Veilwalker, Ranger
Compel Truth 2 30 ft Forces target to answer truthfully (target must pass a WIS save, or the effect applies). Whisperbound, Cleric
Dazzling Veil 1 30 ft cone Blinds enemies in a cone for 1 round (target must pass a WIS save). Veilwalker, Ranger
Deathgate 3 60 ft Opens a portal to summon skeletal arms; restrains target (target must pass a STR save). Necromancer, Cleric
Death Whispers 1 60 ft Frightens the target (target must pass a WIS save to avoid panic). Necromancer, Whisperbound
Detect Magic 1 30 ft Reveals magical auras around objects and creatures. Arcane, Ranger, Cleric
Divine Light 1 30 ft Deals Step 2 radiant damage and slightly heals nearby allies. Cleric, Paladin, Ranger
Drain Life 2 30 ft Deals Step 2 damage and heals you for an amount proportional to the damage dealt. Necromancer, Cleric
Dream Echo 2 Touch Implants a false memory; the target is confused for 1 round. Veilwalker, Whisperbound
Eldritch Bolt 2 60 ft Deals Step 3 psychic damage. Whisperbound, Arcane
Eye of the Void 2 Self Grants vision of invisible or magical auras for 1 minute. Whisperbound, Arcane, Ranger
Forbidden Words 1 Self Enhances the next spell’s Target Number by +1, making it harder for targets to resist. Whisperbound, Cleric
Ghoul Claws 2 Melee Deals Step 3 damage; target must succeed on a save or be paralyzed for 1 round. Necromancer
Grave Hunger 2 30 ft Summons spectral jaws dealing Step 2 damage per round (requires concentration). Necromancer
Healing Word 1 30 ft Restores 1d4 plus stat bonus HP to one ally. Cleric, Paladin
Invisibility 3 Touch Grants invisibility for 1 minute, or until you attack. Arcane, Veilwalker
Lightning Ray 2 60 ft Fires a ray that deals Step 3 damage and may arc to a second target. Arcane, Paladin
Life Ward 2 Self Absorbs up to 1d6 damage for a short duration. Cleric, Paladin
Mage Step 1 10 ft Teleports you to a visible point. Arcane, Veilwalker, Ranger
Magic Missile 1 60 ft Automatically hits and deals Step 2 damage. Arcane, Paladin, Ranger
Mental Probe 1 30 ft Reads surface thoughts; deeper insight requires a WIS save. Whisperbound, Arcane
Mirror Image 2 Self Creates 2 illusory duplicates that can confuse attackers. Veilwalker, Arcane
Mind Shatter 3 60 ft Deals Step 4 psychic damage and stuns the target on a failed save. Whisperbound, Necromancer
Phantom Blade 2 Melee Deals Step 3 damage; bypasses some armor bonuses. Veilwalker, Arcane, Paladin
Primal Roar 2 30 ft Forces enemies within 10 ft to make a fear check (WIS save required). Ranger, Paladin
Radiant Burst 3 30 ft radius Deals Step 3 radiant damage to all enemies within the area. Cleric, Paladin, Ranger
Raise Dead 2 10 ft Animates an undead minion (1 HD, 1 HP); lasts 1 scene. Necromancer, Cleric, Paladin
Sacred Barrier 2 Self Grants +3 Soak for 1 minute. Cleric, Paladin
Smite 2 Melee Deals extra radiant damage (Step 3) and forces a saving throw. Paladin, Cleric
Soul Leech 3 30 ft Deals Step 2 damage; if target dies, you regain 1 MP. Whisperbound, Necromancer
Spell Echo 3 Self Recasts your last spell at -1 MP cost (usable once per scene). Arcane, Whisperbound
Spirit Sense 1 Self Detects nearby undead and lingering souls. Necromancer, Cleric
Shadow Grasp 2 60 ft Deals Step 2 damage and restrains the target (target must pass a STR save). Veilwalker, Necromancer
Shadowstep 1 30 ft Teleports you between shadows. Veilwalker, Arcane
Thought Thief 2 30 ft Steals a spell from the target (they lose it for 1 hour; target must pass an INT save to resist). Whisperbound, Necromancer
Tranquil Mind 1 Self Reduces incoming damage by 1 Step for 1 round. Monk, Ranger
Umbral Chains 3 60 ft Binds up to 3 enemies; targets must pass a WIS save to escape. Veilwalker, Necromancer, Ranger
Whispering Madness 2 30 ft Confuses 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.

End of article

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