diff -Naur nethack-3.4.3/src/muse.c nethack-cancel/src/muse.c
--- nethack-3.4.3/src/muse.c	2003-12-08 10:39:13.000000000 +1100
+++ nethack-cancel/src/muse.c	2003-12-20 13:12:34.000000000 +1100
@@ -957,6 +957,7 @@
 /*#define MUSE_WAN_TELEPORTATION 15*/
 #define MUSE_POT_SLEEPING 16
 #define MUSE_SCR_EARTH 17
+#define MUSE_WAN_CANCELLATION 18
 
 /* Select an offensive item/action for a monster.  Returns TRUE iff one is
  * found.
@@ -1034,6 +1035,11 @@
 			m.offensive = obj;
 			m.has_offense = MUSE_WAN_STRIKING;
 		}
+                nomore(MUSE_WAN_CANCELLATION);
+                if(obj->otyp == WAN_CANCELLATION && obj->spe > 0) {
+                        m.offensive = obj;
+                        m.has_offense = MUSE_WAN_CANCELLATION;
+                }
 		nomore(MUSE_POT_PARALYSIS);
 		if(obj->otyp == POT_PARALYSIS && multi >= 0) {
 			m.offensive = obj;
@@ -1308,6 +1314,7 @@
 		return (mtmp->mhp <= 0) ? 1 : 2;
 	case MUSE_WAN_TELEPORTATION:
 	case MUSE_WAN_STRIKING:
+        case MUSE_WAN_CANCELLATION:
 		zap_oseen = oseen;
 		mzapmsg(mtmp, otmp, FALSE);
 		otmp->spe--;
diff -Naur nethack-3.4.3/src/zap.c nethack-cancel/src/zap.c
--- nethack-3.4.3/src/zap.c	2003-12-08 10:39:13.000000000 +1100
+++ nethack-cancel/src/zap.c	2003-12-20 13:38:40.000000000 +1100
@@ -804,6 +804,17 @@
 	}
 }
 
+boolean cancellable(obj)
+register struct obj *obj;
+{
+   return objects[obj->otyp].oc_magic
+       || (obj->spe && (obj->oclass == ARMOR_CLASS ||
+                        obj->oclass == WEAPON_CLASS || is_weptool(obj)))
+       || obj->otyp == POT_ACID 
+       || obj->otyp == POT_SICKNESS;
+
+}
+
 /* cancel obj, possibly carried by you or a monster */
 void
 cancel_item(obj)
@@ -854,6 +865,40 @@
 			break;
 		/* case RIN_PROTECTION:  not needed */
 	}
+
+
+        /* MRKR: Cancelled *DSM reverts to scales.  */
+        /*       Suggested by Daniel Morris in RGRN */
+
+        if (obj->otyp >= GRAY_DRAGON_SCALE_MAIL &&
+            obj->otyp <= YELLOW_DRAGON_SCALE_MAIL) {
+            /* dragon scale mail reverts to dragon scales */
+
+           boolean worn = (obj == uarm);
+
+           if (!Blind) {
+               char buf[BUFSZ];
+               pline("%s %s reverts to natural form!", 
+                      Shk_Your(buf, obj), xname(obj));
+           }
+           else if (worn) {
+               Your("armor feels looser.");
+           }
+           costly_cancel(obj);
+
+           if (worn) {
+                setworn((struct obj *)0, W_ARM);
+           }
+
+           /* assumes same order */
+             obj->otyp = GRAY_DRAGON_SCALES +
+                         obj->otyp - GRAY_DRAGON_SCALE_MAIL;
+
+           if (worn) {
+                 setworn(obj, W_ARM);
+           }
+        }
+ 
 	if (objects[obj->otyp].oc_magic
 	    || (obj->spe && (obj->oclass == ARMOR_CLASS ||
 			     obj->oclass == WEAPON_CLASS || is_weptool(obj)))
@@ -904,6 +949,7 @@
 	return;
 }
 
+
 /* Remove a positive enchantment or charge from obj,
  * possibly carried by you or a monster
  */
@@ -2248,6 +2294,36 @@
 		find_ac();
 	    }
 	}
+        else {  /* select one random item to cancel */
+	    struct obj *otmp;
+            int count = 0;
+ 
+            for (otmp = (youdefend ? invent : mdef->minvent); 
+                 otmp; otmp = otmp->nobj) {
+                 if (cancellable(otmp)) {
+			count++;
+		 }
+            }
+
+            if (count > 0) {
+		int o = rnd(count);
+            
+                for (otmp = (youdefend ? invent : mdef->minvent);
+                    otmp; otmp = otmp->nobj) {
+                    if (cancellable(otmp)) {
+			o--;
+                        if (o == 0) {
+				cancel_item(otmp);
+ 				break;
+                        }
+                    }
+                }
+                if (youdefend) {
+                   flags.botl = 1; /* potential AC change */
+                   find_ac();
+                }
+	    }
+        }
 
 	/* now handle special cases */
 	if (youdefend) {