All auto-generated monsters in ice caves should start with cold immunity.

defs.h

@@ -4964,6 +4964,7 @@ typedef struct habitat_s {
 	enum OBTYPE upstairtype, downstairtype;
 	int stairsinrooms;
 	enum CELLTYPE emptycelltype,solidcelltype;
+	struct flagpile_s *monflags; // random monsters in this habitat get these
 	struct habitat_s *next, *prev;
 } habitat_t;
 

map.c

@@ -648,6 +648,10 @@ int addrandomthing(cell_t *c, int obchance, int *nadded) {
 		lf = addmonster(c, R_RANDOM, NULL, B_TRUE, 1, B_TRUE, B_ALLOWEXTRA, nadded);
 		if (lf) {
 			rv = TT_MONSTER;
+			if (c->habitat) {
+				// ensure it has proper resistances
+				copyflags(lf->flags, c->habitat->monflags, NA);
+			}
 		} 
 		//if (gamemode == GM_GAMESTARTED) checkallflags(player->cell->map); // debugging
 	}
@@ -5866,6 +5870,31 @@ void killcell(cell_t **c) {
 //	}
 }
 
+void killbranch(branch_t *b) {
+	branch_t *nextone, *lastone;
+	// free mem
+	free(b->name);
+	
+	// remove from list
+        nextone = b->next;
+        if (nextone != NULL) {
+                nextone->prev = b->prev;
+        } else { /* last */
+                lastbranch = b->prev;
+        }
+
+        if (b->prev == NULL) {
+                /* first */
+                nextone = b->next;
+                free(firstbranch);
+                firstbranch = nextone;
+        } else {
+                lastone = b->prev;
+                free (lastone->next );
+                lastone->next = nextone;
+        }
+}
+
 void killcelltype(celltype_t *ct) {
 	celltype_t *nextone, *lastone;
 	if (ct->name) free(ct->name);
@@ -5896,6 +5925,33 @@ void killfakes(map_t *map, cell_t *cell) {
 	free(map->name);
 }
 
+void killhabitat(habitat_t *h) {
+	habitat_t *nextone, *lastone;
+	// free mem
+	free(h->name);
+	killflagpile(h->monflags);
+	h->monflags = NULL;
+	
+	// remove from list
+        nextone = h->next;
+        if (nextone != NULL) {
+                nextone->prev = h->prev;
+        } else { /* last */
+                lasthabitat = h->prev;
+        }
+
+        if (h->prev == NULL) {
+                /* first */
+                nextone = h->next;
+                free(firsthabitat);
+                firsthabitat = nextone;
+        } else {
+                lastone = h->prev;
+                free (lastone->next );
+                lastone->next = nextone;
+        }
+}
+
 void killmap(map_t *m) {
 	map_t *nextone, *lastone;
 	int i;
@@ -8812,10 +8868,12 @@ object_t *hastrailof(obpile_t *op, lifeform_t *lf, int oid, flag_t **tflag, life
 
 
 void initmap(void) {
+	habitat_t *h;
 	// habitats
 	//                    thingchance, obchance, vaultchance, maxvisrange, upstiartype, downstairtype, stairs_in_rooms,temp
 	addhabitat(H_DUNGEON, "dungeon", CT_CORRIDOR, CT_WALL, 5, 60, 40, 6, OT_STAIRSUP, OT_STAIRSDOWN, B_TRUE, T_NORMAL);
-	addhabitat(H_ICECAVE, "ice cavern", CT_CORRIDOR, CT_WALLICE, 10, 45, 20, 6, OT_ICESTAIRSUP, OT_ICESTAIRSDOWN, B_FALSE, T_COLD);
+	h = addhabitat(H_ICECAVE, "ice cavern", CT_CORRIDOR, CT_WALLICE, 10, 45, 20, 6, OT_ICESTAIRSUP, OT_ICESTAIRSDOWN, B_FALSE, T_COLD);
+		addflag(h->monflags, F_DTIMMUNE, DT_COLD, B_TRUE, NA, NULL);
 	addhabitat(H_CAVE, "cave", CT_DIRT, CT_WALLDIRT, 5, 45, 20, 6, OT_TUNNELUP, OT_TUNNELDOWN, B_FALSE, T_NORMAL);
 	addhabitat(H_FOREST, "forest", CT_GRASS, CT_WALLTREE, 5, 75, 0, MAXVISRANGE, OT_TREEUP, OT_TREEDOWN, B_FALSE, T_NORMAL);
 	addhabitat(H_HEAVEN, "heaven", CT_CORRIDOR, CT_WALLGLASS, 5, 0, 0, MAXVISRANGE, OT_NONE, OT_NONE, B_FALSE, T_NORMAL);
@@ -8874,6 +8932,7 @@ void initmap(void) {
 	addbranch(BH_WOODS, "The Sylvan Woods", B_TRUE, H_FOREST, 3, 3, D_DOWN, B_TRUE, 1, B_FALSE);
 	addbranch(BH_MASTERVAULTS, "The Master Vaults", B_TRUE, H_MASTERVAULTS, 3, 1, D_DOWN, B_TRUE, 5, B_TRUE);
 	addbranch(BH_ICECAVERNS, "The Ice Caverns", B_TRUE, H_ICECAVE, 1, 1, D_DOWN, B_TRUE, 10, B_FALSE);
+
 	// minor branches
 	addbranch(BH_PIT, "A Pit", B_FALSE, H_PIT, 1, 1, D_DOWN, B_FALSE, 0, B_TRUE);
 	addbranch(BH_SEWER, "A Sewer", B_FALSE, H_SEWER, 1, 0, D_NONE, B_FALSE, 2, B_TRUE);

map.h

@@ -185,9 +185,11 @@ int isoutdoors(map_t *m);
 int isroom(cell_t *c);
 int issolid(cell_t *c);
 int iswallindir(cell_t *cell, int dir);
+void killbranch(branch_t *b);
 void killcell(cell_t **c);
 void killcelltype(celltype_t *ct);
 void killfakes(map_t *map, cell_t *cell);
+void killhabitat(habitat_t *h);
 void killmap(map_t *m);
 void killregion(region_t *r);
 int linkexit(cell_t *c, int wantfilled, int *ncellsadded);

nexus.c

@@ -914,6 +914,8 @@ void cleanup(void) {
 	while (firstoption) killoption(firstoption);
 	// free maps (this will kill its lifeforms & obs & cells too)
 	while (firstmap) killmap(firstmap);
+	// free branches
+	while (firstbranch) killbranch(firstbranch);
 	// free knowledge
 	while (knowledge) killknowledge(knowledge);
 	// free brands