diff --git a/src/main/java/com/sk89q/worldedit/LocalSession.java b/src/main/java/com/sk89q/worldedit/LocalSession.java
index e0f147028..0c5696b8e 100644
--- a/src/main/java/com/sk89q/worldedit/LocalSession.java
+++ b/src/main/java/com/sk89q/worldedit/LocalSession.java
@@ -686,6 +686,9 @@ public class LocalSession {
                 new EditSession(player.isPlayer() ? player.getWorld() : null,
                         getBlockChangeLimit(), blockBag);
         editSession.setFastMode(fastMode);
+        if (mask != null) {
+            mask.prepare(this, player, null);
+        }
         editSession.setMask(mask);
 
         return editSession;
diff --git a/src/main/java/com/sk89q/worldedit/WorldEdit.java b/src/main/java/com/sk89q/worldedit/WorldEdit.java
index 827d4ec98..da4de3b79 100644
--- a/src/main/java/com/sk89q/worldedit/WorldEdit.java
+++ b/src/main/java/com/sk89q/worldedit/WorldEdit.java
@@ -600,6 +600,10 @@ public class WorldEdit {
         case '#':
             if (component.equalsIgnoreCase("#existing")) {
                 return new ExistingBlockMask();
+            } else if (component.equalsIgnoreCase("#dregion")
+                    || component.equalsIgnoreCase("#dselection")
+                    || component.equalsIgnoreCase("#dsel")) {
+                return new DynamicRegionMask();
             } else if (component.equalsIgnoreCase("#selection")
                     || component.equalsIgnoreCase("#region")
                     || component.equalsIgnoreCase("#sel")) {
diff --git a/src/main/java/com/sk89q/worldedit/masks/BiomeTypeMask.java b/src/main/java/com/sk89q/worldedit/masks/BiomeTypeMask.java
index 6331a7591..c25621f17 100644
--- a/src/main/java/com/sk89q/worldedit/masks/BiomeTypeMask.java
+++ b/src/main/java/com/sk89q/worldedit/masks/BiomeTypeMask.java
@@ -5,6 +5,8 @@ import java.util.Set;
 
 import com.sk89q.worldedit.BiomeType;
 import com.sk89q.worldedit.EditSession;
+import com.sk89q.worldedit.LocalPlayer;
+import com.sk89q.worldedit.LocalSession;
 import com.sk89q.worldedit.Vector;
 
 public class BiomeTypeMask implements Mask {
@@ -19,6 +21,9 @@ public class BiomeTypeMask implements Mask {
         this.biomes = biomes;
     }
 
+    public void prepare(LocalSession session, LocalPlayer player, Vector target) {
+    }
+
     public boolean matches(EditSession editSession, Vector pos) {
         BiomeType biome = editSession.getWorld().getBiome(pos.toVector2D());
         return biomes.contains(biome);
diff --git a/src/main/java/com/sk89q/worldedit/masks/BlockTypeMask.java b/src/main/java/com/sk89q/worldedit/masks/BlockTypeMask.java
index b3ebfe3fc..ce2ed7c52 100644
--- a/src/main/java/com/sk89q/worldedit/masks/BlockTypeMask.java
+++ b/src/main/java/com/sk89q/worldedit/masks/BlockTypeMask.java
@@ -22,6 +22,8 @@ package com.sk89q.worldedit.masks;
 import java.util.HashSet;
 import java.util.Set;
 import com.sk89q.worldedit.EditSession;
+import com.sk89q.worldedit.LocalPlayer;
+import com.sk89q.worldedit.LocalSession;
 import com.sk89q.worldedit.Vector;
 
 /**
@@ -49,6 +51,9 @@ public class BlockTypeMask implements Mask {
         types.add(type);
     }
 
+    public void prepare(LocalSession session, LocalPlayer player, Vector target) {
+    }
+
     public boolean matches(EditSession editSession, Vector pos) {
         return types.contains(editSession.getBlockType(pos));
     }
diff --git a/src/main/java/com/sk89q/worldedit/masks/CombinedMask.java b/src/main/java/com/sk89q/worldedit/masks/CombinedMask.java
index 4bb5e070a..fa618a81d 100644
--- a/src/main/java/com/sk89q/worldedit/masks/CombinedMask.java
+++ b/src/main/java/com/sk89q/worldedit/masks/CombinedMask.java
@@ -22,6 +22,8 @@ package com.sk89q.worldedit.masks;
 import java.util.ArrayList;
 import java.util.List;
 import com.sk89q.worldedit.EditSession;
+import com.sk89q.worldedit.LocalPlayer;
+import com.sk89q.worldedit.LocalSession;
 import com.sk89q.worldedit.Vector;
 
 public class CombinedMask implements Mask {
@@ -51,6 +53,12 @@ public class CombinedMask implements Mask {
         return masks.contains(mask);
     }
 
+    public void prepare(LocalSession session, LocalPlayer player, Vector target) {
+        for (Mask mask : masks) {
+            mask.prepare(session, player, target);
+        }
+    }
+
     public boolean matches(EditSession editSession, Vector pos) {
         for (Mask mask : masks) {
             if (!mask.matches(editSession, pos)) {
diff --git a/src/main/java/com/sk89q/worldedit/masks/DynamicRegionMask.java b/src/main/java/com/sk89q/worldedit/masks/DynamicRegionMask.java
new file mode 100644
index 000000000..c7cec61d3
--- /dev/null
+++ b/src/main/java/com/sk89q/worldedit/masks/DynamicRegionMask.java
@@ -0,0 +1,26 @@
+package com.sk89q.worldedit.masks;
+
+import com.sk89q.worldedit.EditSession;
+import com.sk89q.worldedit.IncompleteRegionException;
+import com.sk89q.worldedit.LocalPlayer;
+import com.sk89q.worldedit.LocalSession;
+import com.sk89q.worldedit.Vector;
+import com.sk89q.worldedit.regions.Region;
+
+public class DynamicRegionMask implements Mask {
+
+    private Region region;
+
+    public void prepare(LocalSession session, LocalPlayer player, Vector target) {
+        try {
+            region = session.getSelection(player.getWorld());
+        } catch (IncompleteRegionException exc) {
+            region = null;
+        }
+    }
+
+    @Override
+    public boolean matches(EditSession editSession, Vector pos) {
+        return region == null || region.contains(pos);
+    }
+}
diff --git a/src/main/java/com/sk89q/worldedit/masks/ExistingBlockMask.java b/src/main/java/com/sk89q/worldedit/masks/ExistingBlockMask.java
index 3f4827b95..cd5be8199 100644
--- a/src/main/java/com/sk89q/worldedit/masks/ExistingBlockMask.java
+++ b/src/main/java/com/sk89q/worldedit/masks/ExistingBlockMask.java
@@ -20,10 +20,16 @@
 package com.sk89q.worldedit.masks;
 
 import com.sk89q.worldedit.EditSession;
+import com.sk89q.worldedit.LocalPlayer;
+import com.sk89q.worldedit.LocalSession;
 import com.sk89q.worldedit.Vector;
 import com.sk89q.worldedit.blocks.BlockID;
 
 public class ExistingBlockMask implements Mask {
+
+    public void prepare(LocalSession session, LocalPlayer player, Vector target) {
+    }
+
     public boolean matches(EditSession editSession, Vector pos) {
         return editSession.getBlockType(pos) != BlockID.AIR;
     }
diff --git a/src/main/java/com/sk89q/worldedit/masks/Mask.java b/src/main/java/com/sk89q/worldedit/masks/Mask.java
index d1ac39766..322ffdb72 100644
--- a/src/main/java/com/sk89q/worldedit/masks/Mask.java
+++ b/src/main/java/com/sk89q/worldedit/masks/Mask.java
@@ -20,6 +20,8 @@
 package com.sk89q.worldedit.masks;
 
 import com.sk89q.worldedit.EditSession;
+import com.sk89q.worldedit.LocalPlayer;
+import com.sk89q.worldedit.LocalSession;
 import com.sk89q.worldedit.Vector;
 
 /**
@@ -29,6 +31,16 @@ import com.sk89q.worldedit.Vector;
  * @author sk89q
  */
 public interface Mask {
+
+    /**
+     * Called one time before each edit session.
+     *
+     * @param session
+     * @param player
+     * @param target target of the brush, null if not a brush mask
+     */
+    public void prepare(LocalSession session, LocalPlayer player, Vector target);
+
     /**
      * Given a block position, this method returns true if the block at
      * that position matches the filter. Block information is not provided
diff --git a/src/main/java/com/sk89q/worldedit/masks/RegionMask.java b/src/main/java/com/sk89q/worldedit/masks/RegionMask.java
index f949b01a5..18cad9683 100644
--- a/src/main/java/com/sk89q/worldedit/masks/RegionMask.java
+++ b/src/main/java/com/sk89q/worldedit/masks/RegionMask.java
@@ -20,6 +20,8 @@
 package com.sk89q.worldedit.masks;
 
 import com.sk89q.worldedit.EditSession;
+import com.sk89q.worldedit.LocalPlayer;
+import com.sk89q.worldedit.LocalSession;
 import com.sk89q.worldedit.Vector;
 import com.sk89q.worldedit.regions.Region;
 
@@ -31,6 +33,9 @@ public class RegionMask implements Mask {
         this.region = region.clone();
     }
 
+    public void prepare(LocalSession session, LocalPlayer player, Vector target) {
+    }
+
     public boolean matches(EditSession editSession, Vector pos) {
         return region.contains(pos);
     }
diff --git a/src/main/java/com/sk89q/worldedit/masks/UnderOverlayMask.java b/src/main/java/com/sk89q/worldedit/masks/UnderOverlayMask.java
index 5d5b339b5..f8a3a3815 100644
--- a/src/main/java/com/sk89q/worldedit/masks/UnderOverlayMask.java
+++ b/src/main/java/com/sk89q/worldedit/masks/UnderOverlayMask.java
@@ -23,6 +23,8 @@ import java.util.HashSet;
 import java.util.Set;
 
 import com.sk89q.worldedit.EditSession;
+import com.sk89q.worldedit.LocalPlayer;
+import com.sk89q.worldedit.LocalSession;
 import com.sk89q.worldedit.Vector;
 import com.sk89q.worldedit.blocks.BlockID;
 
@@ -44,6 +46,9 @@ public class UnderOverlayMask implements Mask {
         this.ids.addAll(ids);
     }
 
+    public void prepare(LocalSession session, LocalPlayer player, Vector target) {
+    }
+
     public boolean matches(EditSession editSession, Vector pos) {
         int id = editSession.getBlock(pos.setY(pos.getBlockY() + (overlay ? -1 : 1))).getType();
         return ids.isEmpty() ? id != BlockID.AIR : ids.contains(id);
diff --git a/src/main/java/com/sk89q/worldedit/tools/BrushTool.java b/src/main/java/com/sk89q/worldedit/tools/BrushTool.java
index 121242118..100036e2f 100644
--- a/src/main/java/com/sk89q/worldedit/tools/BrushTool.java
+++ b/src/main/java/com/sk89q/worldedit/tools/BrushTool.java
@@ -178,6 +178,7 @@ public class BrushTool implements TraceTool {
 
         EditSession editSession = session.createEditSession(player);
         if (mask != null) {
+            mask.prepare(session, player, target);
             Mask existingMask = editSession.getMask();
             if (existingMask == null) {
                 editSession.setMask(mask);