diff --git a/include/context.h b/include/context.h
index 6209a5e82..4e20f3bdc 100644
--- a/include/context.h
+++ b/include/context.h
@@ -1,4 +1,4 @@
-/* NetHack 3.6	context.h	$NHDT-Date: 1455907260 2016/02/19 18:41:00 $  $NHDT-Branch: NetHack-3.6.0 $:$NHDT-Revision: 1.30 $ */
+/* NetHack 3.6	context.h	$NHDT-Date: 1575775592 2019/12/08 03:26:32 $  $NHDT-Branch: NetHack-3.7 $:$NHDT-Revision: 1.35 $ */
 /* Copyright (c) Stichting Mathematisch Centrum, Amsterdam, 1985. */
 /*-Copyright (c) Michael Allison, 2006. */
 /* NetHack may be freely redistributed.  See license for details. */
@@ -115,6 +115,7 @@ struct context_info {
     int current_fruit; /* fruit->fid corresponding to g.pl_fruit[] */
     int warnlevel;
     int rndencode;          /* randomized escape sequence introducer */
+    int mysteryforce;
     long next_attrib_check; /* next attribute check */
     long stethoscope_move;
     short stethoscope_movement;
diff --git a/include/patchlevel.h b/include/patchlevel.h
index 0c8bd7c7a..94fac6a63 100644
--- a/include/patchlevel.h
+++ b/include/patchlevel.h
@@ -1,4 +1,4 @@
-/* NetHack 3.7	patchlevel.h	$NHDT-Date: 1574982020 2019/11/28 23:00:20 $  $NHDT-Branch: NetHack-3.7 $:$NHDT-Revision: 1.134 $ */
+/* NetHack 3.7	patchlevel.h	$NHDT-Date: 1575775596 2019/12/08 03:26:36 $  $NHDT-Branch: NetHack-3.7 $:$NHDT-Revision: 1.136 $ */
 /* Copyright (c) Stichting Mathematisch Centrum, Amsterdam, 1985. */
 /*-Copyright (c) Michael Allison, 2012. */
 /* NetHack may be freely redistributed.  See license for details. */
@@ -14,7 +14,7 @@
  * Incrementing EDITLEVEL can be used to force invalidation of old bones
  * and save files.
  */
-#define EDITLEVEL 1
+#define EDITLEVEL 2
 
 #define COPYRIGHT_BANNER_A "NetHack, Copyright 1985-2019"
 #define COPYRIGHT_BANNER_B \
diff --git a/src/do.c b/src/do.c
index 9b5cbd965..4dcc8ca07 100644
--- a/src/do.c
+++ b/src/do.c
@@ -1,4 +1,4 @@
-/* NetHack 3.6	do.c	$NHDT-Date: 1575245055 2019/12/02 00:04:15 $  $NHDT-Branch: NetHack-3.6 $:$NHDT-Revision: 1.196 $ */
+/* NetHack 3.6	do.c	$NHDT-Date: 1575775597 2019/12/08 03:26:37 $  $NHDT-Branch: NetHack-3.7 $:$NHDT-Revision: 1.216 $ */
 /* Copyright (c) Stichting Mathematisch Centrum, Amsterdam, 1985. */
 /*-Copyright (c) Derek S. Ray, 2015. */
 /* NetHack may be freely redistributed.  See license for details. */
@@ -1279,15 +1279,22 @@ boolean at_stairs, falling, portal;
      *   -1   11.46  12.50  12.5
      *   -2    5.21   4.17   0.0
      *   -3    2.08   0.0    0.0
+     *
+     * 3.7.0: the chance for the "mysterious force" to kick in goes down
+     * as it kicks in, starting at 25% per climb attempt and dropping off
+     * gradually but substantially.  The drop off is greater when hero is
+     * sent down farther so benefits lawfuls more than chaotics this time.
      */
     if (Inhell && up && u.uhave.amulet && !newdungeon && !portal
         && (dunlev(&u.uz) < dunlevs_in_dungeon(&u.uz) - 3)) {
-        if (!rn2(4)) {
+        if (!rn2(4 + g.context.mysteryforce)) {
             int odds = 3 + (int) u.ualign.type,   /* 2..4 */
-                diff = odds <= 1 ? 0 : rn2(odds); /* paranoia */
+                diff = (odds <= 1) ? 0 : rn2(odds); /* paranoia */
 
             if (diff != 0) {
                 assign_rnd_level(newlevel, &u.uz, diff);
+                /* assign_rnd_level() may have used a value less than diff */
+                diff = u.uz.dlevel - newlevel->dlevel; /* actual descent */
                 /* if inside the tower, stay inside */
                 if (was_in_W_tower && !On_W_tower_level(newlevel))
                     diff = 0;
@@ -1295,15 +1302,20 @@ boolean at_stairs, falling, portal;
             if (diff == 0)
                 assign_level(newlevel, &u.uz);
 
-            new_ledger = ledger_no(newlevel);
-
             pline("A mysterious force momentarily surrounds you...");
+            /* each time it kicks in, the chance of doing so again may drop;
+               that drops faster, on average, when being sent down farther so
+               while the impact is reduced for everybody compared to earlier
+               versions, it is reduced least for chaotics, most for lawfuls */
+            g.context.mysteryforce += rn2(diff + 2); /* L:0-4, N:0-3, C:0-2 */
+
             if (on_level(newlevel, &u.uz)) {
                 (void) safe_teleds(FALSE);
                 (void) next_to_u();
                 return;
-            } else
-                at_stairs = g.at_ladder = FALSE;
+            }
+            new_ledger = ledger_no(newlevel);
+            at_stairs = g.at_ladder = FALSE;
         }
     }