Core/Scripts: fix Nightfall proc chance and reduce it for victims with level above 60

Port From (https://github.com/TrinityCore/TrinityCore/commit/5f70be050f971ee70da8953c4f094cb2adc233f8)

Source/Game/Entities/Player/Player.Spells.cs

@@ -3304,7 +3304,7 @@ namespace Game.Entities
                     else if (chance > 100.0f)
                         chance = GetWeaponProcChance();
 
-                    if (RandomHelper.randChance(chance))
+                    if (RandomHelper.randChance(chance) && Global.ScriptMgr.OnCastItemCombatSpell(this, damageInfo.GetVictim(), spellInfo, item))
                         CastSpell(damageInfo.GetVictim(), spellInfo.Id, true, item);
                 }
             }

Source/Game/Scripting/CoreScripts.cs

@@ -279,6 +279,12 @@ namespace Game.Scripting
 
         // Called when the item expires (is destroyed).
         public virtual bool OnExpire(Player player, ItemTemplate proto) { return false; }
+
+        // Called when the item is destroyed.
+        public virtual bool OnRemove(Player player, Item item) { return false; }
+
+        // Called before casting a combat spell from this item (chance on hit spells of item template, can be used to prevent cast if returning false)
+        public virtual bool OnCastItemCombatSpell(Player player, Unit victim, SpellInfo spellInfo, Item item) { return true; }
     }
 
     public class UnitScript : ScriptObject

Source/Game/Scripting/ScriptManager.cs

@@ -738,6 +738,22 @@ namespace Game.Scripting
 
             return RunScriptRet<ItemScript>(p => p.OnExpire(player, proto), proto.ScriptId);
         }
+        public bool OnItemRemove(Player player, Item item)
+        {
+            Cypher.Assert(player != null);
+            Cypher.Assert(item != null);
+
+            return RunScriptRet<ItemScript>(tmpscript => tmpscript.OnRemove(player, item), item.GetScriptId());
+        }
+        public bool OnCastItemCombatSpell(Player player, Unit victim, SpellInfo spellInfo, Item item)
+        {
+            Cypher.Assert(player != null);
+            Cypher.Assert(victim != null);
+            Cypher.Assert(spellInfo != null);
+            Cypher.Assert(item != null);
+
+            return RunScriptRet<ItemScript>(tmpscript => tmpscript.OnCastItemCombatSpell(player, victim, spellInfo, item), item.GetScriptId());
+        }
 
         //CreatureScript
         public bool OnDummyEffect(Unit caster, uint spellId, uint effIndex, Creature target)

Source/Scripts/World/ItemScripts.cs

@@ -360,4 +360,27 @@ namespace Scripts.World
             return true;
         }
     }
+
+    // Only used currently for
+    [Script]// 19169: Nightfall
+    class item_generic_limit_chance_above_60 : ItemScript
+    {
+        public item_generic_limit_chance_above_60() : base("item_generic_limit_chance_above_60") { }
+
+        public override bool OnCastItemCombatSpell(Player player, Unit victim, SpellInfo spellInfo, Item item)
+        {
+            // spell proc chance gets severely reduced on victims > 60 (formula unknown)
+            if (victim.getLevel() > 60)
+            {
+                // gives ~0.1% proc chance at lvl 70
+                float lvlPenaltyFactor = 9.93f;
+                float failureChance = (victim.GetLevelForTarget(player) - 60) * lvlPenaltyFactor;
+
+                // base ppm chance was already rolled, only roll success chance
+                return !RandomHelper.randChance(failureChance);
+            }
+
+            return true;
+        }
+    }
 }