diff --git a/OpenRA.Mods.Cnc/OpenRA.Mods.Cnc.csproj b/OpenRA.Mods.Cnc/OpenRA.Mods.Cnc.csproj
index 762a7a7d93..30340c17aa 100644
--- a/OpenRA.Mods.Cnc/OpenRA.Mods.Cnc.csproj
+++ b/OpenRA.Mods.Cnc/OpenRA.Mods.Cnc.csproj
@@ -159,6 +159,7 @@
     <Compile Include="Traits\Attack\AttackTDGunboatTurreted.cs" />
     <Compile Include="Traits\GpsDot.cs" />
     <Compile Include="Traits\ConyardChronoReturn.cs" />
+    <Compile Include="Traits\TransferTimedExternalConditionOnTransform.cs" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\OpenRA.Game\OpenRA.Game.csproj">
diff --git a/OpenRA.Mods.Cnc/Traits/TransferTimedExternalConditionOnTransform.cs b/OpenRA.Mods.Cnc/Traits/TransferTimedExternalConditionOnTransform.cs
new file mode 100644
index 0000000000..7a966d9410
--- /dev/null
+++ b/OpenRA.Mods.Cnc/Traits/TransferTimedExternalConditionOnTransform.cs
@@ -0,0 +1,64 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2018 The OpenRA Developers (see AUTHORS)
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version. For more
+ * information, see COPYING.
+ */
+#endregion
+
+using System.Linq;
+using OpenRA.Mods.Common.Traits;
+using OpenRA.Traits;
+
+namespace OpenRA.Mods.Cnc.Traits
+{
+	[Desc("A special case trait that re-grants a timed external condition when this actor transforms.",
+		"This trait does not work with permanently granted external conditions.",
+		"This trait changes the external condition source, so cannot be used for conditions that may later be revoked")]
+	public class TransferTimedExternalConditionOnTransformInfo : ITraitInfo, Requires<TransformsInfo>
+	{
+		[FieldLoader.Require]
+		[Desc("External condition to transfer")]
+		public readonly string Condition = null;
+
+		public object Create(ActorInitializer init) { return new TransferTimedExternalConditionOnTransform(this); }
+	}
+
+	public class TransferTimedExternalConditionOnTransform : IConditionTimerWatcher, INotifyTransform
+	{
+		readonly TransferTimedExternalConditionOnTransformInfo info;
+		int duration = 0;
+		int remaining = 0;
+
+		public TransferTimedExternalConditionOnTransform(TransferTimedExternalConditionOnTransformInfo info)
+		{
+			this.info = info;
+		}
+
+		void INotifyTransform.BeforeTransform(Actor self) { }
+		void INotifyTransform.OnTransform(Actor self) { }
+
+		void INotifyTransform.AfterTransform(Actor toActor)
+		{
+			if (remaining <= 0)
+				return;
+
+			var external = toActor.TraitsImplementing<ExternalCondition>()
+				.FirstOrDefault(t => t.Info.Condition == info.Condition && t.CanGrantCondition(toActor, this));
+
+			if (external != null)
+				external.GrantCondition(toActor, this, duration, remaining);
+		}
+
+		void IConditionTimerWatcher.Update(int duration, int remaining)
+		{
+			this.duration = duration;
+			this.remaining = remaining;
+		}
+
+		string IConditionTimerWatcher.Condition { get { return info.Condition; } }
+	}
+}
diff --git a/OpenRA.Mods.Common/Traits/Conditions/ExternalCondition.cs b/OpenRA.Mods.Common/Traits/Conditions/ExternalCondition.cs
index a8a98ac0b1..84a684edcb 100644
--- a/OpenRA.Mods.Common/Traits/Conditions/ExternalCondition.cs
+++ b/OpenRA.Mods.Common/Traits/Conditions/ExternalCondition.cs
@@ -91,7 +91,7 @@ namespace OpenRA.Mods.Common.Traits
 			return true;
 		}
 
-		public int GrantCondition(Actor self, object source, int duration = 0)
+		public int GrantCondition(Actor self, object source, int duration = 0, int remaining = 0)
 		{
 			if (!CanGrantCondition(self, source))
 				return ConditionManager.InvalidConditionToken;
@@ -100,6 +100,11 @@ namespace OpenRA.Mods.Common.Traits
 			HashSet<int> permanent;
 			permanentTokens.TryGetValue(source, out permanent);
 
+			// Callers can override the amount of time remaining by passing a value
+			// between 1 and the duration
+			if (remaining <= 0 || remaining > duration)
+				remaining = duration;
+
 			if (duration > 0)
 			{
 				// Check level caps
@@ -137,7 +142,7 @@ namespace OpenRA.Mods.Common.Traits
 					}
 				}
 
-				var timedToken = new TimedToken(token, self, source, duration);
+				var timedToken = new TimedToken(token, self, source, remaining);
 				var index = timedTokens.FindIndex(t => t.Expires >= timedToken.Expires);
 				if (index >= 0)
 					timedTokens.Insert(index, timedToken);
diff --git a/mods/ra/rules/structures.yaml b/mods/ra/rules/structures.yaml
index 130895235e..0653b2a4f1 100644
--- a/mods/ra/rules/structures.yaml
+++ b/mods/ra/rules/structures.yaml
@@ -1136,6 +1136,8 @@ FACT:
 	ConyardChronoReturn:
 		Condition: chrono-vortex
 		Damage: 950
+	TransferTimedExternalConditionOnTransform:
+		Condition: invulnerability
 
 PROC:
 	Inherits: ^Building
diff --git a/mods/ra/rules/vehicles.yaml b/mods/ra/rules/vehicles.yaml
index 94b1b2654a..0c5e28b8ff 100644
--- a/mods/ra/rules/vehicles.yaml
+++ b/mods/ra/rules/vehicles.yaml
@@ -368,6 +368,8 @@ MCV:
 		Actor: MCV.Husk
 		OwnerType: InternalName
 		EffectiveOwnerFromOwner: true
+	TransferTimedExternalConditionOnTransform:
+		Condition: invulnerability
 
 JEEP:
 	Inherits: ^Vehicle