diff --git a/SPD-classes/src/main/java/com/watabou/utils/PointF.java b/SPD-classes/src/main/java/com/watabou/utils/PointF.java
index f5352412a..b1d5654fe 100644
--- a/SPD-classes/src/main/java/com/watabou/utils/PointF.java
+++ b/SPD-classes/src/main/java/com/watabou/utils/PointF.java
@@ -151,6 +151,10 @@ public class PointF {
 		return (float)Math.atan2( end.y - start.y, end.x - start.x );
 	}
 
+	public static float angle( Point start, Point end ) {
+		return (float)Math.atan2( end.y - start.y, end.x - start.x );
+	}
+
 	@Override
 	public boolean equals(Object o) {
 		if (super.equals(o))
diff --git a/core/src/main/java/com/shatteredpixel/shatteredpixeldungeon/actors/mobs/VaultMob.java b/core/src/main/java/com/shatteredpixel/shatteredpixeldungeon/actors/mobs/VaultMob.java
new file mode 100644
index 000000000..424c2d429
--- /dev/null
+++ b/core/src/main/java/com/shatteredpixel/shatteredpixeldungeon/actors/mobs/VaultMob.java
@@ -0,0 +1,140 @@
+package com.shatteredpixel.shatteredpixeldungeon.actors.mobs;
+
+import com.shatteredpixel.shatteredpixeldungeon.Dungeon;
+import com.shatteredpixel.shatteredpixeldungeon.actors.Char;
+import com.watabou.utils.Bundle;
+import com.watabou.utils.PointF;
+
+public class VaultMob extends Mob {
+
+	{
+		WANDERING = new Wandering();
+		INVESTIGATING = new Investigating();
+		SLEEPING = new Sleeping();
+
+		state = SLEEPING;
+	}
+
+	//used to track
+	private int previousPos;
+
+	@Override
+	public void move(int step, boolean travelling) {
+		previousPos = pos;
+		super.move(step, travelling);
+	}
+
+	private static final String PREV_POS = "prev_pos";
+	private static final String INVEST_TURNS = "invest_turns";
+
+	@Override
+	public void storeInBundle(Bundle bundle) {
+		super.storeInBundle(bundle);
+		bundle.put(PREV_POS, previousPos);
+		bundle.put(INVEST_TURNS, investigatingTurns);
+	}
+
+	@Override
+	public void restoreFromBundle(Bundle bundle) {
+		super.restoreFromBundle(bundle);
+		previousPos = bundle.getInt(PREV_POS);
+		investigatingTurns = bundle.getInt(INVEST_TURNS);
+	}
+
+	private int investigatingTurns;
+
+	public class Investigating extends Mob.Investigating {
+
+		@Override
+		public boolean act(boolean enemyInFOV, boolean justAlerted) {
+			if (enemyInFOV){
+				investigatingTurns++;
+			} else {
+				investigatingTurns = 0;
+			}
+			return super.act(enemyInFOV, justAlerted);
+		}
+
+		@Override
+		//TODO balance this
+		//chance is 1 in (distance/2 + stealth) as base, but reduced if enemy was only just seen
+		protected float detectionChance( Char enemy ){
+			float chance = 1 / (distance( enemy ) / 2f + enemy.stealth());
+			if (investigatingTurns == 1 && chance <= 1){
+				chance -= 0.33f;
+			}
+			return chance;
+		}
+	}
+
+	public class Wandering extends Mob.Wandering {
+
+		@Override
+		public boolean act(boolean enemyInFOV, boolean justAlerted) {
+			return super.act(enemyInFOV, justAlerted);
+		}
+
+		@Override
+		protected float detectionChance( Char enemy ){
+			//defaults to 1 in (distance + stealth) (classic sleeping detection)
+			if (!Dungeon.level.adjacent(pos, previousPos)){
+				return 1 / (distance( enemy ) + enemy.stealth());
+			}
+
+			float movementDir = PointF.angle(Dungeon.level.cellToPoint(previousPos), Dungeon.level.cellToPoint(pos))/PointF.G2R;;
+			float enemyDir = PointF.angle(Dungeon.level.cellToPoint(pos), Dungeon.level.cellToPoint(enemy.pos))/PointF.G2R;
+			//classic wandering detection if enemy is within a 90 degree cone of vision
+			if (Math.abs(enemyDir - movementDir) <= 45f){
+				return 1 / (distance( enemy ) / 2f + enemy.stealth());
+			//classic sleeping (i.e. default) detection if enemy is within a 170 degree vision cone
+			} else if (Math.abs(enemyDir - movementDir) <= 85f){
+				return 1 / (distance( enemy ) + enemy.stealth());
+			//otherwise uses very low chance detection (1/8 at 2 tiles, 0% at 3+)
+			} else {
+				float chance = 1 / (float)Math.pow((distance( enemy ) + enemy.stealth()), 3);
+				if (chance < 0.1f){
+					return 0;
+				} else {
+					return chance;
+				}
+			}
+		}
+
+		@Override
+		protected boolean noticeEnemy() {
+			super.noticeEnemy();
+			alerted = false;
+			state = INVESTIGATING;
+			investigatingTurns = 0;
+			sprite.showInvestigate();
+			spend(TICK);
+			return true;
+		}
+	}
+
+	public class Sleeping extends Mob.Sleeping{
+
+		protected void awaken(boolean enemyInFOV) {
+			super.awaken(enemyInFOV);
+			if (state == HUNTING){
+				alerted = false;
+				state = INVESTIGATING;
+				investigatingTurns = 0;
+				sprite.showInvestigate();
+			}
+		}
+
+		//chance is 1 in (distance + stealth)^2
+		//set to 0 if below 10% (usually happens at 4+ distance)
+		@Override
+		protected float detectionChance( Char enemy ){
+			float chance = 1 / (float)Math.pow((distance( enemy ) + enemy.stealth()), 2);
+			if (chance < 0.1f){
+				return 0;
+			} else {
+				return chance;
+			}
+		}
+	}
+
+}