ModernUO/dev-docs/claude-skills/modernuo-content-patterns.md

name	description
modernuo-content-patterns	Trigger when creating new items, mobiles, creatures, spells, skills, loot tables, or any game content under Projects/UOContent/. This is the hub skill that connects to all other ModernUO skills.

ModernUO Content Patterns (Hub Skill)

When This Activates

• Creating new items, weapons, armor, clothing, containers
• Creating new creatures, NPCs, vendors
• Creating new spells
• Implementing skill handlers
• Adding loot tables
• Adding context menus
• Any new game content under Projects/UOContent/

Key Rules

1. Always ask target era if the user hasn't specified (see modernuo-era-expansion.md)
2. All serializable classes must be partial with [SerializationGenerator]
3. All Item/Mobile constructors need [Constructible]
4. Clean up timers and references in OnDelete()/OnAfterDelete()
5. No LINQ in game logic -- use loops and PooledRefList<T>
6. File placement matters -- follow the directory conventions below
7. Creature speeds are delays in seconds, on two clocks -- think (ActiveSpeed/PassiveSpeed, seconds per AI decision) and move (ActiveMoveSpeed/PassiveMoveSpeed, seconds per step; inherits think until overridden). Prefer npc-speeds.json buckets (SpeedClass); SetSpeed() sets think AND clears move overrides, SetMoveSpeed() sets move only. Herding and pacing to a master (FollowMoveSpeed) cap the resolved pace without writing either clock. The client Running bit is derived from the step pace (BaseAI.ShouldRun); movement APIs take no run argument -- see dev-docs/content-patterns.md § Creature Speeds. Reaction time to approaching enemies is AcquireOnApproachDelay (TimeSpan gradient; Zero = paragon snap, 2s default, ReacquireDelay-only = oblivious) -- see § Target Acquisition
8. OnThink overrides must be excess-call tolerant -- it fires more often than the think cadence (player commands prod it; speed-ups reschedule it). Gate consequential work on a tick-count deadline (subtraction form) or make it idempotent; bare per-call random rolls are cosmetics-only. MonsterAbility is under the same contract: the trigger cooldown is the rate limit, ChanceToTrigger is per-sample jitter, and a zero-cooldown Think/CombatAction ability triggers every sampled think -- see dev-docs/content-patterns.md § OnThink: the excess-call contract

New Item Template

using ModernUO.Serialization;

namespace Server.Items;

[SerializationGenerator(0)]
public partial class MyItem : Item
{
    [Constructible]
    public MyItem() : base(0x1234)  // itemID from art
    {
        Weight = 1.0;
        // Stackable = true;  // if stackable
        // Amount = 1;         // if stackable
    }

    public override string DefaultName => "a my item";
    // OR: public override int LabelNumber => 1234567;  // cliloc number

    public override void OnDoubleClick(Mobile from)
    {
        if (!IsChildOf(from.Backpack))
        {
            from.SendLocalizedMessage(1042001); // Must be in backpack
            return;
        }

        // Item use logic
    }

    public override void GetProperties(IPropertyList list)
    {
        base.GetProperties(list);
        // list.Add(1060741, $"{_charges}");  // charges: ~1_val~
    }
}

New Creature Template

using ModernUO.Serialization;
using Server.Items;

namespace Server.Mobiles;

[SerializationGenerator(0)]
public partial class MyCreature : BaseCreature
{
    [Constructible]
    public MyCreature() : base(AIType.AI_Melee, FightMode.Closest)
    {
        Body = 0;           // Body graphic ID
        BaseSoundID = 0;    // Base sound ID

        SetStr(100, 150);   // Strength min/max
        SetDex(80, 100);    // Dexterity min/max
        SetInt(30, 50);     // Intelligence min/max

        SetHits(80, 120);
        SetMana(0);

        SetDamage(8, 14);

        SetDamageType(ResistanceType.Physical, 100);

        SetResistance(ResistanceType.Physical, 30, 40);
        SetResistance(ResistanceType.Fire, 10, 20);
        SetResistance(ResistanceType.Cold, 10, 20);
        SetResistance(ResistanceType.Poison, 15, 25);
        SetResistance(ResistanceType.Energy, 10, 20);

        SetSkill(SkillName.MagicResist, 30.0, 50.0);
        SetSkill(SkillName.Tactics, 50.0, 70.0);
        SetSkill(SkillName.Wrestling, 50.0, 70.0);

        Fame = 1000;
        Karma = -1000;  // Negative = evil, positive = good, 0 = neutral

        VirtualArmor = 30;
    }

    public override string CorpseName => "a creature corpse";
    public override string DefaultName => "a creature";

    // Optional overrides:
    // public override int Meat => 1;
    // public override int Hides => 8;
    // public override HideType HideType => HideType.Regular;
    // public override FoodType FavoriteFood => FoodType.Meat;
    // public override PackInstinct PackInstinct => PackInstinct.Canine;
    // public override bool CanRummageCorpses => true;
    // public override Poison PoisonImmune => Poison.Lesser;
    // public override Poison HitPoison => Poison.Regular;

    public override void GenerateLoot()
    {
        AddLoot(LootPack.Average);
        AddLoot(LootPack.Gems, 1);
        // PackItem(new SpecificItem());
        // PackGold(50, 100);
    }
}

Tameable Creature Additions

// In constructor:
Tamable = true;
ControlSlots = 1;      // 1-5, how many pet slots it uses
MinTameSkill = 35.1;   // Required Animal Taming skill

AI Types

AIType	Behavior
AI_Melee	Charges into melee combat
AI_Mage	Casts spells, keeps distance
AI_Archer	Uses ranged attacks
AI_Animal	Passive, flees or fights back
AI_Predator	Hunts other creatures
AI_Healer	Heals allies
AI_Vendor	NPC vendor behavior
AI_Berserk	Aggressive, attacks everything
AI_Thief	Steals from players

Fight Modes

FightMode	Target Selection
None	Never attacks
Aggressor	Only attacks those who attack first
Strongest	Targets highest stats
Weakest	Targets lowest stats
Closest	Targets nearest entity
Evil	Attacks aggressors or negative-karma entities

New Spell Template

using System;
using Server.Targeting;

namespace Server.Spells.First;

public class MySpell : MagerySpell, ITargetingSpell<Mobile>
{
    private static readonly SpellInfo _info = new(
        "Spell Name",      // Display name
        "In Vas Ort",       // Power words (mantra)
        212,                // Cast animation action
        9041,               // Cast sound
        Reagent.Bloodmoss,  // Required reagents
        Reagent.MandrakeRoot
    );

    public MySpell(Mobile caster, Item scroll = null) : base(caster, scroll, _info)
    {
    }

    public override SpellCircle Circle => SpellCircle.First;

    public void Target(Mobile m)
    {
        if (CheckHSequence(m))  // Harmful spell check
        {
            SpellHelper.Turn(Caster, m);

            double damage = GetNewAosDamage(10, 1, 4, m);

            SpellHelper.Damage(this, m, damage, 0, 100, 0, 0, 0);
            // Damage types: phys, fire, cold, poison, energy (must sum to 100)
        }
    }

    public override void OnCast()
    {
        Caster.Target = new SpellTarget<Mobile>(this, TargetFlags.Harmful);
    }
}

Spell Circles (Magery)

Circle	Mana Cost	Min Skill
First	4	-50.0 (Pre-ML) / -46.0 (ML+)
Second	6	-30.0 / -32.0
Third	9	0.0 / -18.0
Fourth	11	10.0 / -4.0
Fifth	14	20.0 / 10.0
Sixth	20	30.0 / 24.0
Seventh	40	40.0 / 38.0
Eighth	50	50.0 / 52.0

Skill Implementation

using Server.Targeting;

namespace Server.Skills;

public static class MySkillHandler
{
    public static void Initialize()
    {
        // Register handler delegate
        SkillInfo.Table[(int)SkillName.Alchemy].Callback = OnUse;
    }

    public static TimeSpan OnUse(Mobile from)
    {
        from.SendMessage("You begin working...");
        from.Target = new InternalTarget();
        return TimeSpan.FromSeconds(1.0);  // Delay before next use
    }

    private class InternalTarget : Target
    {
        public InternalTarget() : base(2, false, TargetFlags.None)
        {
        }

        protected override void OnTarget(Mobile from, object targeted)
        {
            if (targeted is Item item)
            {
                // from.CheckSkill(SkillName.Alchemy, minSkill, maxSkill)
                if (from.CheckSkill(SkillName.Alchemy, 0.0, 100.0))
                {
                    from.SendMessage("Success!");
                }
                else
                {
                    from.SendMessage("You fail.");
                }
            }
        }
    }
}

Loot Packs

Use predefined packs -- they auto-select era-appropriate loot:

public override void GenerateLoot()
{
    AddLoot(LootPack.Poor);       // ~50 gold equivalent
    AddLoot(LootPack.Meager);     // ~100 gold equivalent
    AddLoot(LootPack.Average);    // ~250 gold equivalent
    AddLoot(LootPack.Rich);       // ~500 gold equivalent
    AddLoot(LootPack.FilthyRich); // ~1000 gold equivalent
    AddLoot(LootPack.UltraRich);  // ~2000 gold equivalent
    AddLoot(LootPack.SuperBoss);  // Boss-level loot

    AddLoot(LootPack.Gems, 2);    // 2 random gems
    AddLoot(LootPack.Potions);    // Random potion

    // Specific items
    PackItem(new Arrow(Utility.RandomMinMax(20, 40)));
    PackGold(100, 200);
}

Context Menus

public override void GetContextMenuEntries(Mobile from, ref PooledRefList<ContextMenuEntry> list)
{
    base.GetContextMenuEntries(from, ref list);

    if (from.Alive && from.InRange(this, 2))
    {
        list.Add(new MyContextMenuEntry(this));
    }
}

private class MyContextMenuEntry : ContextMenuEntry
{
    private readonly Item _item;

    public MyContextMenuEntry(Item item) : base(6100)  // Cliloc number
    {
        _item = item;
    }

    public override void OnClick(Mobile from, IEntity target)
    {
        // Handle click
    }
}

Two-Phase Deletion

public override void OnDelete()
{
    _timerToken.Cancel();   // Cancel timers FIRST
    base.OnDelete();
}

public override void OnAfterDelete()
{
    _timer?.Stop();         // Stop Timer references
    _timer = null;
    _owner = null;          // Clear Mobile/Item references
    base.OnAfterDelete();
}

File Placement

Content Type	Directory
Items	Projects/UOContent/Items/{Category}/
Weapons	Projects/UOContent/Items/Weapons/{Type}/
Armor	Projects/UOContent/Items/Armor/{Type}/
Creatures	Projects/UOContent/Mobiles/{Type}/
Animals	Projects/UOContent/Mobiles/Animals/{Species}/
Monsters	Projects/UOContent/Mobiles/Monsters/{Era}/
Spells	Projects/UOContent/Spells/{School}/
Skills	Projects/UOContent/Skills/
Engines	Projects/UOContent/Engines/{SystemName}/
Gumps	Projects/UOContent/Gumps/

Real Examples

• Simple creature: Projects/UOContent/Mobiles/Animals/Bears/BlackBear.cs
• Boss creature: Projects/UOContent/Mobiles/Special/Barracoon.cs
• SE creature: Projects/UOContent/Mobiles/Monsters/SE/RaiJu.cs
• Spell: Projects/UOContent/Spells/First/MagicArrow.cs
• Skill check: Projects/UOContent/Skills/SkillCheck.cs
• Loot packs: Projects/UOContent/Misc/LootPack.cs

See Also

• dev-docs/claude-skills/modernuo-serialization.md - Serialization details
• dev-docs/claude-skills/modernuo-era-expansion.md - Era-conditional code
• dev-docs/claude-skills/modernuo-timers.md - Timer patterns
• dev-docs/claude-skills/modernuo-property-lists.md - Item tooltips
• dev-docs/claude-skills/modernuo-gump-system.md - UI dialogs
• dev-docs/claude-skills/modernuo-commands-targeting.md - Commands and targeting
• dev-docs/claude-skills/modernuo-events.md - Event system
• dev-docs/content-patterns.md - Full content documentation