From 4e25c74cdf327272514b7298d15f3d65a659b866 Mon Sep 17 00:00:00 2001
From: Kamron Batman <3953314+kamronbatman@users.noreply.github.com>
Date: Tue, 22 Apr 2025 17:52:09 -0700
Subject: [PATCH] fix: Fixes magical barrier NPE and an edge case (#2162)

---
 .../Mobiles/Abilities/MagicalBarrier.cs       | 32 +++++++++++--------
 1 file changed, 18 insertions(+), 14 deletions(-)

diff --git a/Projects/UOContent/Mobiles/Abilities/MagicalBarrier.cs b/Projects/UOContent/Mobiles/Abilities/MagicalBarrier.cs
index 585a7695b..2069448be 100644
--- a/Projects/UOContent/Mobiles/Abilities/MagicalBarrier.cs
+++ b/Projects/UOContent/Mobiles/Abilities/MagicalBarrier.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Runtime.CompilerServices;
 
 namespace Server.Mobiles;
 
@@ -7,7 +8,7 @@ public class MagicalBarrier : MonsterAbility
 {
     private HashSet<Mobile> _inactiveField;
 
-    public bool HasField(Mobile source) => !_inactiveField.Contains(source);
+    public bool HasField(Mobile source) => _inactiveField?.Contains(source) != true;
 
     public override MonsterAbilityType AbilityType => MonsterAbilityType.MagicalBarrier;
 
@@ -17,17 +18,20 @@ public class MagicalBarrier : MonsterAbility
     public override TimeSpan MinTriggerCooldown => TimeSpan.FromSeconds(10.0);
     public override TimeSpan MaxTriggerCooldown => TimeSpan.FromSeconds(10.0);
 
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static bool CanUseField(BaseCreature source) => source.Hits >= source.HitsMax * 9 / 10;
+
     // Regeneration is subject to the cooldown, the rest are not.
     public override bool CanTrigger(BaseCreature source, MonsterAbilityTrigger trigger) =>
         trigger != MonsterAbilityTrigger.Think || base.CanTrigger(source, trigger);
 
     public override void Trigger(MonsterAbilityTrigger trigger, BaseCreature source, Mobile target)
     {
-        if (trigger == MonsterAbilityTrigger.Think && !source.IsHurt())
+        if (trigger == MonsterAbilityTrigger.Think)
         {
-            var fieldUp = _inactiveField?.Remove(source) == true;
-            if (fieldUp)
+            if (CanUseField(source) && _inactiveField?.Remove(source) == true)
             {
+                // Field going up!
                 source.FixedParticles(0, 10, 0, 0x2530, EffectLayer.Waist);
 
                 if (_inactiveField?.Count == 0)
@@ -36,6 +40,15 @@ public class MagicalBarrier : MonsterAbility
                 }
             }
         }
+        else if (trigger is MonsterAbilityTrigger.TakeSpellDamage && !CanUseField(source))
+        {
+            _inactiveField ??= [];
+            if (_inactiveField.Add(source))
+            {
+                // TODO: message and effect when field turns down; cannot be verified on OSI due to a bug
+                source.FixedParticles(0x3735, 1, 30, 0x251F, EffectLayer.Waist);
+            }
+        }
 
         base.Trigger(trigger, source, target);
     }
@@ -53,22 +66,13 @@ public class MagicalBarrier : MonsterAbility
 
     public override void AlterSpellDamageFrom(BaseCreature source, Mobile target, ref int damage)
     {
-        var canUseField = source.Hits >= source.HitsMax * 9 / 10;
-        // If we cannot use the field, deactivate it.
-        var fieldActive = canUseField ? HasField(source) : _inactiveField.Add(source);
-
-        if (!fieldActive)
+        if (!HasField(source))
         {
             damage = 0; // no spell damage when the field is down
             // should there be an effect when spells nullifying is on?
             source.FixedParticles(0, 10, 0, 0x2522, EffectLayer.Waist);
             target.SendLocalizedMessage(1114359); // Your attack has no effect on the creature's armor.
         }
-        else if (!canUseField)
-        {
-            // TODO: message and effect when field turns down; cannot be verified on OSI due to a bug
-            source.FixedParticles(0x3735, 1, 30, 0x251F, EffectLayer.Waist);
-        }
     }
 
     public override void Move(BaseCreature source, Direction d)