--- name: skill-system description: | Implements skill mechanics, balancing, and player ability handling for L2J Interlude. Use when: creating new skills, modifying skill effects, implementing balance changes, debugging skill execution, or adding skill handlers allowed-tools: Read, Edit, Write, Glob, Grep, Bash --- # Skill System The L2J skill system uses a layered architecture: XML definitions → SkillTable registry → ISkillHandler execution → Effect application. Skills are parsed at startup, cached in memory with a composite key (`skillId * 256 + level`), and executed through type-based handler dispatch. ## Quick Start ### Define a Physical Damage Skill (XML) ```xml 25 27 30 39 42 46 60 65 70 <\/table>

10 10 11 13 13 14 17 18 19 <\/table> <\/skill> ``` ### Create a Skill Handler ```java \/\/ Files\/java\/net\/sf\/l2j\/gameserver\/handler\/skillhandlers\/MyHandler.java public class MyHandler implements ISkillHandler { private static final L2SkillType[] SKILL_IDS = { L2SkillType.MY_TYPE }; @Override public void useSkill(Creature activeChar, L2Skill skill, L2Object[] targets) { if (activeChar.isAlikeDead()) return; for (L2Object obj : targets) { if (!(obj instanceof Creature)) continue; Creature target = (Creature) obj; int damage = (int) Formulas.calcPhysDam(activeChar, target, skill, shld, crit, ss); target.reduceCurrentHp(damage, activeChar, skill); } } @Override public L2SkillType[] getSkillIds() { return SKILL_IDS; } } ``` ### Balance a Skill (No Code Changes) ```xml <\/skill> ``` ## Key Concepts | Concept | Location | Purpose | |---------|----------|---------| | L2SkillType | `templates\/skills\/L2SkillType.java` | Enum mapping skill types to handlers | | SkillTable | `datatables\/SkillTable.java` | Singleton registry, loads XML at startup | | ISkillHandler | `handler\/ISkillHandler.java` | Strategy interface for skill execution | | EffectTemplate | `skills\/effects\/EffectTemplate.java` | Reflection-based effect factory | | Formulas | `skills\/Formulas.java` | Damage, hit chance, critical calculations | | SkillBalanceHolder | `balance\/skills\/SkillBalanceHolder.java` | Runtime balance modifiers | ## Common Patterns ### Add Buff Effect with Stat Modifier ```xml <\/effect> <\/for> <\/skill> ``` ### Apply Balance Multiplier in Handler ```java \/\/ In skill execution code double damage = baseDamage; double powerMul = SkillBalanceHolder.getStat(skill.getId(), "powerMul", 1.0); damage *= powerMul; ``` ## See Also - [patterns](references\/patterns.md) - Handler patterns, effect creation, conditions - [workflows](references\/workflows.md) - Adding skills, balancing, debugging ## Related Skills - **java** skill for Java coding conventions and singleton patterns - **xml-data** skill for XML parsing and data file structure - **ai-system** skill for how NPCs\/summons cast skills via AI intentions - **pvp-events** skill for event-specific skill restrictions - **database-schema** skill for skill-related database tables