Merge branch '4.3.4' of https://gitlab.com/trinitycore/TrinityCore_434 into ShatteredWorld

# Conflicts:
#	src/server/scripts/EasternKingdoms/Gilneas/chapter1.cpp
#	src/server/scripts/Kalimdor/LostCityOfTheTolvir/boss_lockmaw_and_augh.cpp
#	src/server/scripts/Kalimdor/LostCityOfTheTolvir/instance_lost_city_of_the_tolvir.cpp
#	src/server/scripts/Kalimdor/LostCityOfTheTolvir/lost_city_of_the_tolvir.h
#	src/server/scripts/Spells/spell_quest.cpp

src/server/game/Spells/Spell.cpp

@@ -2662,9 +2662,7 @@ SpellMissInfo Spell::DoSpellHitOnUnit(Unit* unit, uint32 effectMask, bool scaleA
         diminishLevel = unit->GetDiminishing(diminishGroup);
         DiminishingReturnsType type = m_spellInfo->GetDiminishingReturnsGroupType(triggered);
         // Increase Diminishing on unit, current informations for actually casts will use values above
-        if ((type == DRTYPE_PLAYER &&
-            (unit->GetCharmerOrOwnerPlayerOrPlayerItself() || (unit->GetTypeId() == TYPEID_UNIT && unit->ToCreature()->GetCreatureTemplate()->flags_extra & CREATURE_FLAG_EXTRA_ALL_DIMINISH))) ||
-            type == DRTYPE_ALL)
+        if (type == DRTYPE_ALL || (type == DRTYPE_PLAYER && unit->IsAffectedByDiminishingReturns()))
             unit->IncrDiminishing(m_spellInfo, triggered);
     }
 
@@ -3259,11 +3257,9 @@ void Spell::_cast(bool skipCheck)
     // skip check if done already (for instant cast spells for example)
     if (!skipCheck)
     {
-        uint32 param1 = 0, param2 = 0;
-        SpellCastResult castResult = CheckCast(false, &param1, &param2);
-        if (castResult != SPELL_CAST_OK)
+        auto cleanupSpell = [this, modOwner](SpellCastResult res, uint32* p1 = nullptr, uint32* p2 = nullptr)
         {
-            SendCastResult(castResult, &param1, &param2);
+            SendCastResult(res, p1, p2);
             SendInterrupted(0);
 
             if (modOwner)
@@ -3271,6 +3267,13 @@ void Spell::_cast(bool skipCheck)
 
             finish(false);
             SetExecutedCurrently(false);
+        };
+
+        uint32 param1 = 0, param2 = 0;
+        SpellCastResult castResult = CheckCast(false, &param1, &param2);
+        if (castResult != SPELL_CAST_OK)
+        {
+            cleanupSpell(castResult, &param1, &param2);
             return;
         }
 
@@ -3286,18 +3289,39 @@ void Spell::_cast(bool skipCheck)
                     {
                         // Spell will be cast after completing the trade. Silently ignore at this place
                         my_trade->SetSpell(m_spellInfo->Id, m_CastItem);
-                        SendCastResult(SPELL_FAILED_DONT_REPORT);
-                        SendInterrupted(0);
-
-                        modOwner->SetSpellModTakingSpell(this, false);
-
-                        finish(false);
-                        SetExecutedCurrently(false);
+                        cleanupSpell(SPELL_FAILED_DONT_REPORT);
                         return;
                     }
                 }
             }
         }
+
+        // check diminishing returns (again, only after finish cast bar, tested on retail)
+        if (Unit* target = m_targets.GetUnitTarget())
+        {
+            uint8 aura_effmask = 0;
+            for (uint8 i = 0; i < MAX_SPELL_EFFECTS; ++i)
+                if (m_spellInfo->Effects[i].IsUnitOwnedAuraEffect())
+                    aura_effmask |= 1 << i;
+
+            if (aura_effmask)
+            {
+                bool const triggered = m_triggeredByAuraSpell != nullptr;
+                if (DiminishingGroup diminishGroup = m_spellInfo->GetDiminishingReturnsGroupForSpell(triggered))
+                {
+                    DiminishingReturnsType type = m_spellInfo->GetDiminishingReturnsGroupType(triggered);
+                    if (type == DRTYPE_ALL || (type == DRTYPE_PLAYER && target->IsAffectedByDiminishingReturns()))
+                    {
+                        Unit* caster = m_originalCaster ? m_originalCaster : m_caster;
+                        if (target->HasStrongerAuraWithDR(m_spellInfo, caster, triggered))
+                        {
+                            cleanupSpell(SPELL_FAILED_AURA_BOUNCED);
+                            return;
+                        }
+                    }
+                }
+            }
+        }
     }
 
     // if the spell allows the creature to turn while casting, then adjust server-side orientation to face the target now