RaisePredictiveEvent works.

Needs sequence numbers fixed.

Content.Shared/GameObjects/EntitySystems/SharedCombatModeSystem.cs

@@ -0,0 +1,40 @@
+using Content.Shared.GameObjects.Components.Mobs;
+using Content.Shared.GameObjects.EntitySystemMessages;
+using Content.Shared.Interfaces;
+using Robust.Shared.GameObjects;
+using Robust.Shared.GameObjects.Systems;
+using Robust.Shared.Interfaces.Random;
+using Robust.Shared.IoC;
+using Robust.Shared.Random;
+using Logger = Robust.Shared.Log.Logger;
+
+namespace Content.Shared.GameObjects.EntitySystems
+{
+    public abstract class SharedCombatModeSystem : EntitySystem
+    {
+        public override void Initialize()
+        {
+            base.Initialize();
+
+            SubscribeNetworkEvent<CombatModeSystemMessages.SetCombatModeActiveMessage>(CombatModeActiveHandler);
+            SubscribeLocalEvent<CombatModeSystemMessages.SetCombatModeActiveMessage>(CombatModeActiveHandler);
+        }
+
+        private void CombatModeActiveHandler(CombatModeSystemMessages.SetCombatModeActiveMessage ev, EntitySessionEventArgs eventArgs)
+        {
+            var entity = eventArgs.SenderSession.AttachedEntity;
+
+            if (!entity.TryGetComponent(out SharedCombatModeComponent combatModeComponent))
+            {
+                return;
+            }
+
+            if (IoCManager.Resolve<IModuleManager>().IsServerModule && IoCManager.Resolve<IRobustRandom>().Prob(0.5f))
+            {
+                Logger.Info("Mispredict!");
+                return;
+            }
+            combatModeComponent.IsInCombatMode = ev.Active;
+        }
+    }
+}