*Fix dispel chance mod calculation.

*Fix Escape artist-by Lightguard.

--HG--
branch : trunk

src/game/SpellAuras.cpp

@@ -5066,6 +5066,21 @@ void Aura::HandleShapeshiftBoosts(bool apply)
     m_target->SetHealth(uint32(ceil((double)m_target->GetMaxHealth() * healthPercentage)));*/
 }
 
+bool Aura::GetDispelChance(Spell* spell)
+{
+    // we assume that aura dispel chance is 100% on start
+    // need formula for level difference based chance
+    int32 miss_chance = 100;
+    // Apply dispel mod from aura caster
+    if (Unit *caster = GetCaster())
+    {
+        if ( Player* modOwner = caster->GetSpellModOwner() )
+            modOwner->ApplySpellMod(GetId(), SPELLMOD_RESIST_DISPEL_CHANCE, miss_chance, spell);
+    }
+    // Try dispel
+    return roll_chance_i(miss_chance);
+}
+
 void Aura::HandleAuraEmpathy(bool apply, bool Real)
 {
     if(m_target->GetTypeId() != TYPEID_UNIT)

src/game/SpellAuras.h

@@ -312,6 +312,8 @@ class TRINITY_DLL_SPEC Aura
         void HandleAuraAllowOnlyAbility(bool apply, bool Real);
         void HandleShapeshiftBoosts(bool apply);
 
+        bool GetDispelChance(Spell* spell);
+
         // Allow Apply Aura Handler to modify and access m_AuraDRGroup
         void setDiminishGroup(DiminishingGroup group) { m_AuraDRGroup = group; }
         DiminishingGroup getDiminishGroup() const { return m_AuraDRGroup; }

src/game/SpellEffects.cpp

@@ -3434,18 +3434,10 @@ void Spell::EffectDispel(uint32 i)
             SpellEntry const* spellInfo = aur->GetSpellProto();
             // Base dispel chance
             // TODO: possible chance depend from spell level??
-            int32 miss_chance = 0;
-            // Apply dispel mod from aura caster
-            if (Unit *caster = aur->GetCaster())
-            {
-                if ( Player* modOwner = caster->GetSpellModOwner() )
-                    modOwner->ApplySpellMod(spellInfo->Id, SPELLMOD_RESIST_DISPEL_CHANCE, miss_chance, this);
-            }
-            // Try dispel
-            if (roll_chance_i(miss_chance))
-                fail_list.push_back(aur->GetId());
-            else
+            if (aur->GetDispelChance(this))
                 success_list.push_back(std::pair<uint32,uint64>(aur->GetId(),aur->GetCasterGUID()));
+            else
+                fail_list.push_back(aur->GetId());
             // Remove buff from list for prevent doubles
             for (std::vector<Aura *>::iterator j = dispel_list.begin(); j != dispel_list.end(); )
             {
@@ -4774,6 +4766,15 @@ void Spell::EffectScriptEffect(uint32 effIndex)
                     unitTarget->HandleEmoteCommand(EMOTE_STATE_DANCE);
                     break;
                 }
+                // Escape artist
+                case 20589:
+                {
+                    if(!unitTarget)
+                        return;
+                    // It is said that removing effects by script should include dispel resist mods
+                    unitTarget->RemoveSpellsCausingAuraWithDispel(SPELL_AURA_MOD_ROOT, this);
+                    unitTarget->RemoveSpellsCausingAuraWithDispel(SPELL_AURA_MOD_DECREASE_SPEED, this);
+                }
                 // Mirren's Drinking Hat
                 case 29830:
                 {
@@ -6205,6 +6206,8 @@ void Spell::EffectDispelMechanic(uint32 i)
         next = iter;
         ++next;
         SpellEntry const *spell = sSpellStore.LookupEntry(iter->second->GetSpellProto()->Id);
+        if (!iter->second->GetDispelChance(this))
+            continue;
         if(spell->Mechanic == mechanic || spell->EffectMechanic[iter->second->GetEffIndex()] == mechanic)
         {
             unitTarget->RemoveAurasDueToSpell(spell->Id);

src/game/Unit.cpp

@@ -476,6 +476,28 @@ void Unit::RemoveSpellsCausingAura(AuraType auraType)
     }
 }
 
+void Unit::RemoveSpellsCausingAuraWithDispel(AuraType auraType, Spell * spell)
+{
+    if (auraType >= TOTAL_AURAS) return;
+    AuraList::iterator iter, next;
+    for (iter = m_modAuras[auraType].begin(); iter != m_modAuras[auraType].end(); iter = next)
+    {
+        next = iter;
+        ++next;
+
+        if (*iter)
+        {
+            if (!(*iter)->GetDispelChance(spell))
+                continue;
+            RemoveAurasDueToSpell((*iter)->GetId());
+            if (!m_modAuras[auraType].empty())
+                next = m_modAuras[auraType].begin();
+            else
+                return;
+        }
+    }
+}
+
 void Unit::RemoveAurasWithInterruptFlags(uint32 flag, uint32 except)
 {
     if(!(m_interruptMask & flag))

src/game/Unit.h

@@ -1234,6 +1234,7 @@ class TRINITY_DLL_SPEC Unit : public WorldObject
         void RemoveNotOwnSingleTargetAuras();
 
         void RemoveSpellsCausingAura(AuraType auraType);
+        void RemoveSpellsCausingAuraWithDispel(AuraType auraType, Spell * spell);
         void RemoveRankAurasDueToSpell(uint32 spellId);
         bool RemoveNoStackAurasDueToAura(Aura *Aur);
         void RemoveAurasWithInterruptFlags(uint32 flags, uint32 except = 0);