Reduce #turn undead helpless duration

src/pray.c

@@ -1973,7 +1973,7 @@ doturn()
             }
         }
     }
-    nomul(-5);
+    nomul(-(5 - ((u.ulevel - 1) / 6))); /* -5 .. -1 */
     multi_reason = "trying to turn the monsters";
     nomovemsg = You_can_move_again;
     return 1;