diff --git a/abms.lua b/abms.lua
index 7ac3c8e..219e07b 100644
--- a/abms.lua
+++ b/abms.lua
@@ -14,9 +14,11 @@ local mushrooms = {"flowers:mushroom_brown", "flowers:mushroom_red"}
 local hunger_mod = minetest.get_modpath("hunger")
 
 
+-- all the fun_caves globalstep functions
 minetest.register_globalstep(function(dtime)
 	local time = minetest.get_us_time()
 
+	-- Execute only after an interval.
 	if last_dps_check and time - last_dps_check < dps_delay then
 		return
 	end
@@ -33,7 +35,9 @@ minetest.register_globalstep(function(dtime)
 				end
 				mob.hp_max = math.floor(mob.hp_max * factor)
 				mob.damage = math.floor(mob.damage * factor)
-				--print("Promoting "..mob.name..": "..mob.hp_max.." at "..pos.x..","..pos.y..","..pos.z)
+				if fun_caves.DEBUG then
+					print("Promoting "..mob.name..": "..mob.hp_max.." at "..pos.x..","..pos.y..","..pos.z)
+				end
 				mob.object:set_hp(mob.hp_max)
 				mob.health = mob.hp_max
 				mob.initial_promotion = true
@@ -47,9 +51,8 @@ minetest.register_globalstep(function(dtime)
 	for i = 1, #players do
 		local player = players[i]
 		local pos = player:getpos()
-		local minp = vector.subtract(pos, 0.5)
-		local maxp = vector.add(pos, 0.5)
 
+		-- How many mobs are up at the moment? This is a rough check.
 		if fun_caves.fortress_spawns and #fun_caves.fortress_spawns > 0 and dps_count % monster_delay == 0 then
 			local mob_count = 0
 			for _, mob in pairs(minetest.luaentities) do
@@ -57,24 +60,24 @@ minetest.register_globalstep(function(dtime)
 					local dist = vector.subtract(pos, mob.object:getpos())
 					local dist2 = math.max(math.abs(dist.x), math.abs(dist.y * 5), math.abs(dist.z))
 					if dist2 < 30 then
-						--print(mob.name, dist.y)
 						mob_count = mob_count + 1
-					else
-						--print("* not", mob.name, dist2)
-						--print(dump(dist))
 					end
 				end
 			end
 
+			-- If we need more, spawn them.
 			if mob_count < fortress_mob_count then
-				local pos1, count = minetest.find_nodes_in_area_under_air({x=pos.x-30, y=pos.y-2, z=pos.z-30}, {x=pos.x+30, y=pos.y+2, z=pos.z+30}, {"group:fortress"})
-				if #pos1 > 0 then
-					local pos2 = pos1[math.random(#pos1)]
-					pos2.y = pos2.y + 2
+				local floor_nodes, count = minetest.find_nodes_in_area_under_air({x=pos.x-30, y=pos.y-2, z=pos.z-30}, {x=pos.x+30, y=pos.y+2, z=pos.z+30}, {"group:fortress"})
+				if #floor_nodes > 0 then
+					local new_mob_pos = floor_nodes[math.random(#floor_nodes)]
+					new_mob_pos.y = new_mob_pos.y + 2
+					--------------------------------------
+					-- Mobs are treated exacty the same. Spawn harder ones differently?
+					--------------------------------------
 					local name = fun_caves.fortress_spawns[math.random(#fun_caves.fortress_spawns)]
-					local mob = minetest.add_entity(pos2, name)
+					local mob = minetest.add_entity(new_mob_pos, name)
 					if mob then
-						print("Fun Caves: Spawned "..name.." at ("..pos2.x..","..pos2.y..","..pos2.z..")")
+						print("Fun Caves: Spawned "..name.." at ("..new_mob_pos.x..","..new_mob_pos.y..","..new_mob_pos.z..")")
 					else
 						print("Fun Caves: failed to spawn "..name)
 					end
@@ -82,23 +85,29 @@ minetest.register_globalstep(function(dtime)
 			end
 		end
 
+		-- environmental damage
 		if fun_caves.DEBUG and player:get_hp() < 20 then
+			-- Regenerate the player while testing.
 			print("HP: "..player:get_hp())
 			player:set_hp(20)
 			return
 		else
-			-- Environmental damage from surfaces/hunger
+			local minp = vector.subtract(pos, 0.5)
+			local maxp = vector.add(pos, 0.5)
+
+			-- ... from standing on or near hot objects.
 			local counts =  minetest.find_nodes_in_area(minp, maxp, {"group:surface_hot"})
 			if #counts > 1 then
 				player:set_hp(player:get_hp() - 1)
 			end
 
-			-- Environmental damage from surfaces/hunger
+			-- ... from standing on or near poison.
 			local counts =  minetest.find_nodes_in_area(minp, maxp, {"group:poison"})
 			if #counts > 1 then
 				player:set_hp(player:get_hp() - 1)
 			end
 
+			-- ... from standing on or near cold objects (less often).
 			if dps_count % cold_delay == 0 then
 				counts =  minetest.find_nodes_in_area(minp, maxp, {"group:surface_cold"})
 				if #counts > 1 then
@@ -106,18 +115,22 @@ minetest.register_globalstep(function(dtime)
 				end
 			end
 
-			-- hunger
+			-- ... from hunger (even less often).
 			if dps_count % hunger_delay == 0 then
 				if hunger_mod then
 					hunger.update_hunger(player, hunger.players[player:get_player_name()].lvl - 4)
 				else
 					player:set_hp(player:get_hp() - 1)
 				end
-				dps_count = hunger_delay
 			end
 		end
 	end
 
+	-- Set this outside of the player loop, to affect everyone.
+	if dps_count % hunger_delay == 0 then
+		dps_count = hunger_delay
+	end
+
 	last_dps_check = minetest.get_us_time()
 	dps_count = dps_count - 1
 end)
diff --git a/mobs.lua b/mobs.lua
index 4304814..ffb4e08 100644
--- a/mobs.lua
+++ b/mobs.lua
@@ -164,9 +164,12 @@ end
 -- executed in a mob's do_custom() to regulate their actions
 -- if false, do nothing
 local custom_delay = 5000000
-fun_caves.custom_ready = function(self)
+fun_caves.custom_ready = function(self, delay)
 	local time = minetest.get_us_time()
-	if not self.custom_time or time - self.custom_time > custom_delay then
+	if not delay then
+		delay = custom_delay
+	end
+	if not self.custom_time or time - self.custom_time > delay then
 		self.custom_time = time
 		return true
 	else
@@ -175,6 +178,39 @@ fun_caves.custom_ready = function(self)
 end
 
 
+if minetest.registered_entities["dmobs:fox"] then
+	local function fire_walk(self)
+		if not fun_caves.custom_ready(self, 1000000) then
+			return
+		end
+
+		local pos = self.object:getpos()
+		local p1 = vector.subtract(pos, 1)
+		local p2 = vector.add(pos, 1)
+
+		--look for nodes
+		local nodelist = minetest.find_nodes_in_area(p1, p2, "air")
+		for n in pairs(nodelist) do
+			minetest.set_node(pos, {name='fire:basic_flame'})
+		end
+	end
+
+	local m = table.copy(minetest.registered_entities["dmobs:fox"])
+	m.name = 'fun_caves:fire_fox'
+	m.damage = 3
+	--hp_min = 42,
+	--hp_max = 52,
+	m.lava_damage = 0
+	m.textures = { {"fun_caves_fire_fox_2.png"}, }
+	m.base_texture = m.textures[1]
+	m.do_custom = fire_walk
+
+	minetest.registered_entities["fun_caves:fire_fox"] = m
+	mobs.spawning_mobs["fun_caves:fire_fox"] = true
+
+	--mobs:register_spawn("fun_caves:fire_fox", {'default:dirt_with_grass'}, 20, -1, 1000, 5, 31000)
+end
+
 if minetest.registered_entities["mobs:bee"] then
 	local function bee_summon(self)
 		if self.state ~= 'attack' then
diff --git a/textures/fun_caves_fire_fox.png b/textures/fun_caves_fire_fox.png
new file mode 100644
index 0000000..970971c
Binary files /dev/null and b/textures/fun_caves_fire_fox.png differ
diff --git a/textures/fun_caves_fire_fox_2.png b/textures/fun_caves_fire_fox_2.png
new file mode 100644
index 0000000..de66615
Binary files /dev/null and b/textures/fun_caves_fire_fox_2.png differ