diff --git a/mods/CORE/mcl_util/init.lua b/mods/CORE/mcl_util/init.lua
index 1f53feef7..6143bfb41 100644
--- a/mods/CORE/mcl_util/init.lua
+++ b/mods/CORE/mcl_util/init.lua
@@ -48,6 +48,20 @@ function table.pairs_by_keys(t, f)
 	return iter
 end
 
+-- Removes one element randomly selected from the array section of the table and
+-- returns it, or nil if there are no elements in the array section of the table
+function table.remove_random_element(table)
+	local count = #table
+	if count == 0 then return nil end
+
+	local idx = math.random(count)
+	local res = table[idx]
+	table[idx] = table[count]
+	table[count] = nil
+	count = count - 1
+	return res
+end
+
 local LOGGING_ON = minetest.settings:get_bool("mcl_logging_default", false)
 local LOG_MODULE = "[MCL2]"
 function mcl_util.mcl_log(message, module, bypass_default_logger)
diff --git a/mods/ENTITIES/mcl_mobs/breeding.lua b/mods/ENTITIES/mcl_mobs/breeding.lua
index 90e625db8..559195681 100644
--- a/mods/ENTITIES/mcl_mobs/breeding.lua
+++ b/mods/ENTITIES/mcl_mobs/breeding.lua
@@ -105,7 +105,7 @@ end
 
 -- Spawn a child
 function mcl_mobs.spawn_child(pos, mob_type)
-	local child = minetest.add_entity(pos, mob_type)
+	local child = mcl_mobs.spawn(pos, mob_type)
 	if not child then
 		return
 	end
@@ -285,6 +285,7 @@ function mob_class:check_breeding()
 					end
 
 					local child = mcl_mobs.spawn_child(pos, parent1.name)
+					if not child then return end
 
 					local ent_c = child:get_luaentity()
 
diff --git a/mods/ENTITIES/mcl_mobs/init.lua b/mods/ENTITIES/mcl_mobs/init.lua
index 81b5fdfe7..74e6edbec 100644
--- a/mods/ENTITIES/mcl_mobs/init.lua
+++ b/mods/ENTITIES/mcl_mobs/init.lua
@@ -528,7 +528,7 @@ end
 -- Note: This also introduces the “spawn_egg” group:
 -- * spawn_egg=1: Spawn egg (generic mob, no metadata)
 -- * spawn_egg=2: Spawn egg (captured/tamed mob, metadata)
-function mcl_mobs.register_egg(mob, desc, background_color, overlay_color, addegg, no_creative)
+function mcl_mobs.register_egg(mob_id, desc, background_color, overlay_color, addegg, no_creative)
 
 	local grp = {spawn_egg = 1}
 
@@ -539,7 +539,7 @@ function mcl_mobs.register_egg(mob, desc, background_color, overlay_color, addeg
 
 	local invimg = "(spawn_egg.png^[multiply:" .. background_color ..")^(spawn_egg_overlay.png^[multiply:" .. overlay_color .. ")"
 	if old_spawn_icons then
-		local mobname = mob:gsub("mobs_mc:","")
+		local mobname = mob_id:gsub("mobs_mc:","")
 		local fn = "mobs_mc_spawn_icon_"..mobname..".png"
 		if mcl_util.file_exists(minetest.get_modpath("mobs_mc").."/textures/"..fn) then
 			invimg = fn
@@ -551,7 +551,7 @@ function mcl_mobs.register_egg(mob, desc, background_color, overlay_color, addeg
 	end
 
 	-- register old stackable mob egg
-	minetest.register_craftitem(mob, {
+	minetest.register_craftitem(mob_id, {
 
 		description = desc,
 		inventory_image = invimg,
@@ -561,7 +561,6 @@ function mcl_mobs.register_egg(mob, desc, background_color, overlay_color, addeg
 		_doc_items_usagehelp = S("Just place it where you want the mob to appear. Animals will spawn tamed, unless you hold down the sneak key while placing. If you place this on a mob spawner, you change the mob it spawns."),
 
 		on_place = function(itemstack, placer, pointed_thing)
-
 			local pos = pointed_thing.above
 
 			-- am I clicking on something with existing on_rightclick function?
@@ -571,11 +570,12 @@ function mcl_mobs.register_egg(mob, desc, background_color, overlay_color, addeg
 				return def.on_rightclick(pointed_thing.under, under, placer, itemstack)
 			end
 
+			local mob_name = itemstack:get_name()
+
 			if pos and within_limits(pos, 0)  and not minetest.is_protected(pos, placer:get_player_name()) then
 				local name = placer:get_player_name()
 				local privs = minetest.get_player_privs(name)
 
-
 				if under.name == "mcl_mobspawners:spawner" then
 					if minetest.is_protected(pointed_thing.under, name) then
 						minetest.record_protection_violation(pointed_thing.under, name)
@@ -593,7 +593,6 @@ function mcl_mobs.register_egg(mob, desc, background_color, overlay_color, addeg
 					--minetest.log("max light: " .. mob_light_lvl[2])
 
 					-- Handle egg conversion
-					local mob_name = itemstack:get_name()
 					local convert_to = (minetest.registered_entities[mob_name] or {})._convert_to
 					if convert_to then mob_name = convert_to end
 
@@ -604,19 +603,24 @@ function mcl_mobs.register_egg(mob, desc, background_color, overlay_color, addeg
 					return itemstack
 				end
 
-				if not minetest.registered_entities[mob] then
+				if not minetest.registered_entities[mob_name] then
 					return itemstack
 				end
 
 				if minetest.settings:get_bool("only_peaceful_mobs", false)
-						and minetest.registered_entities[mob].type == "monster" then
+						and minetest.registered_entities[mob_name].type == "monster" then
 					minetest.chat_send_player(name, S("Only peaceful mobs allowed!"))
 					return itemstack
 				end
 
-				pos.y = pos.y - 0.5
+				pos.y = pos.y - 1
+				local mob = mcl_mobs.spawn(pos, mob_name)
+				if not object then
+					pos.y = pos.y + 1
+					mob = mcl_mobs.spawn(pos, mob_name)
+					if not mob then return end
+				end
 
-				local mob = minetest.add_entity(pos, mob)
 				local entityname = itemstack:get_name()
 				minetest.log("action", "Player " ..name.." spawned "..entityname.." at "..minetest.pos_to_string(pos))
 				local ent = mob:get_luaentity()
@@ -647,5 +651,4 @@ function mcl_mobs.register_egg(mob, desc, background_color, overlay_color, addeg
 			return itemstack
 		end,
 	})
-
 end
diff --git a/mods/ENTITIES/mcl_mobs/spawning.lua b/mods/ENTITIES/mcl_mobs/spawning.lua
index d47b2212f..8436540bf 100644
--- a/mods/ENTITIES/mcl_mobs/spawning.lua
+++ b/mods/ENTITIES/mcl_mobs/spawning.lua
@@ -530,8 +530,8 @@ local function get_water_spawn(p)
 		end
 end
 
-local function has_room(self,pos)
-	local cb = self.collisionbox
+local function has_room(self, pos)
+	local cb = self.spawnbox or self.collisionbox
 	local nodes = {}
 	if self.fly_in then
 		local t = type(self.fly_in)
@@ -542,18 +542,74 @@ local function has_room(self,pos)
 		end
 	end
 	table.insert(nodes,"air")
-	local x = cb[4] - cb[1]
-	local y = cb[5] - cb[2]
-	local z = cb[6] - cb[3]
-	local r = math.ceil(x * y * z)
-	local p1 = vector.offset(pos,cb[1],cb[2],cb[3])
-	local p2 = vector.offset(pos,cb[4],cb[5],cb[6])
-	local n = #minetest.find_nodes_in_area(p1,p2,nodes) or 0
-	if r > n then
-		minetest.log("warning","[mcl_mobs] No room for mob "..self.name.." at "..minetest.pos_to_string(vector.round(pos)))
-		return false
+
+	-- Calculate area to check for room
+	local cb_height = cb[5] - cb[2]
+	local p1 = vector.new(
+		math.round(pos.x + cb[1]),
+		math.floor(pos.y),
+		math.round(pos.z + cb[3]))
+	local p2 = vector.new(
+		math.round(pos.x + cb[4]),
+		math.ceil(p1.y + cb_height) - 1,
+		math.round(pos.z + cb[6]))
+
+	-- Check if the entire spawn volume is free
+	local dx = p2.x - p1.x + 1
+	local dy = p2.y - p1.y + 1
+	local dz = p2.z - p1.z + 1
+	local found_nodes = minetest.find_nodes_in_area(p1,p2,nodes) or 0
+	local n = #found_nodes
+	if n == dx * dy * dz then
+		return true
 	end
-	return true
+
+	-- If we don't have an implementation of get_node_boxes, we can't check for sub-node space
+	if not minetest.get_node_boxes then return false end
+
+	-- Check if it's possible for a sub-node space check to succeed
+	local needed_in_bottom_section = dx * ( dy - 1) * dz
+	if n < needed_in_bottom_section then return false end
+
+	-- Make sure the entire volume except for the top level is free before checking the top layer
+	if dy > 1 then
+		-- Remove nodes in the top layer from the count
+		for i = 1,#found_nodes do
+			if found_nodes[i].y == p2.y then
+				n = n - 1
+			end
+		end
+
+		-- If the entire volume except the top layer isn't air (or nodes) then we can't spawn this mob here
+		if n < needed_in_bottom_section then return false end
+	end
+
+	-- Check the top layer to see if we have enough space to spawn in
+	local top_layer_height = 1
+	local processed = {}
+	for x = p1.x,p2.x do
+		for z = p1.z,p2.z do
+			local test_pos = vector.new(x,p2.y,z)
+			local node = minetest.get_node(test_pos) or { name = "ignore" }
+			local cache_name = string.format("%s-%d", node.name, node.param2)
+			if not processed[cache_name] then
+				-- Calculate node bounding box and select the lowest y value
+				local boxes = minetest.get_node_boxes("collision_box", test_pos, node)
+				for i = 1,#boxes do
+					local box = boxes[i]
+					local y_test = box[2] + 0.5
+					if y_test < top_layer_height then top_layer_height = y_test end
+
+					local y_test = box[5] + 0.5
+					if y_test < top_layer_height then top_layer_height = y_test end
+				end
+			end
+		end
+	end
+	if top_layer_height + dy - 1 >= cb_height then return true end
+
+	-- We don't have room
+	return false
 end
 
 mcl_mobs.custom_biomecheck = nil
@@ -644,10 +700,10 @@ function mcl_mobs.spawn(pos,id)
 	if not pos or not id then return false end
 	local def = minetest.registered_entities[id] or minetest.registered_entities["mobs_mc:"..id] or minetest.registered_entities["extra_mobs:"..id]
 	if not def or not def.is_mob or (def.can_spawn and not def.can_spawn(pos)) then return false end
+	if not has_room(def, pos) then return false end
 	return minetest.add_entity(pos, def.name)
 end
 
-
 local function spawn_group(p,mob,spawn_on,amount_to_spawn)
 	local nn= minetest.find_nodes_in_area_under_air(vector.offset(p,-5,-3,-5),vector.offset(p,5,3,5),spawn_on)
 	local o
diff --git a/mods/ENTITIES/mobs_mc/slime+magma_cube.lua b/mods/ENTITIES/mobs_mc/slime+magma_cube.lua
index fa9d24d09..57eb5a859 100644
--- a/mods/ENTITIES/mobs_mc/slime+magma_cube.lua
+++ b/mods/ENTITIES/mobs_mc/slime+magma_cube.lua
@@ -53,12 +53,14 @@ local spawn_children_on_die = function(child_mob, spawn_distance, eject_speed)
 					eject_speed = eject_speed * 0.5
 				end
 			end
-			local mob = minetest.add_entity(newpos, child_mob)
-			if not mother_stuck then
-				mob:set_velocity(dir * eject_speed)
+			local mob = mcl_mobs.spawn(newpos, child_mob)
+			if mob then
+				if not mother_stuck then
+					mob:set_velocity(dir * eject_speed)
+				end
+				mob:set_yaw(angle - math.pi/2)
+				table.insert(children, mob)
 			end
-			mob:set_yaw(angle - math.pi/2)
-			table.insert(children, mob)
 			angle = angle + (math.pi*2) / spawn_count
 		end
 		-- If mother was murdered, children attack the killer after 1 second
diff --git a/mods/ENTITIES/mobs_mc/spider.lua b/mods/ENTITIES/mobs_mc/spider.lua
index d01c7afbe..7fd8909ba 100644
--- a/mods/ENTITIES/mobs_mc/spider.lua
+++ b/mods/ENTITIES/mobs_mc/spider.lua
@@ -67,6 +67,7 @@ local spider = {
 	curiosity = 10,
 	head_yaw="z",
 	collisionbox = {-0.7, -0.01, -0.7, 0.7, 0.89, 0.7},
+	spawnbox = {-1.2, -0.01, -1.2, 1.2, 0.89, 1.2},
 	visual = "mesh",
 	mesh = "mobs_mc_spider.b3d",
 	textures = {
diff --git a/mods/ENTITIES/mobs_mc/villager.lua b/mods/ENTITIES/mobs_mc/villager.lua
index 47b4cb470..5ea20c707 100644
--- a/mods/ENTITIES/mobs_mc/villager.lua
+++ b/mods/ENTITIES/mobs_mc/villager.lua
@@ -1049,14 +1049,18 @@ local function has_summon_participants(self)
 end
 
 local function summon_golem(self)
-	vector.offset(self.object:get_pos(),-10,-10,-10)
-	local nn = minetest.find_nodes_in_area_under_air(vector.offset(self.object:get_pos(),-10,-10,-10),vector.offset(self.object:get_pos(),10,10,10),{"group:solid","group:water"})
-	table.shuffle(nn)
-	for _,n in pairs(nn) do
-		local up = minetest.find_nodes_in_area(vector.offset(n,0,1,0),vector.offset(n,0,3,0),{"air"})
-		if up and #up >= 3 then
+	local pos = self.object:get_pos()
+	local p1 = vector.offset(pos, -10, -10, -10)
+	local p2 = vector.offset(pos,  10,  10,  10)
+	local nn = minetest.find_nodes_in_area_under_air(p1, p2,{"group:solid","group:water"})
+	while #nn > 0 do
+		local n = table.remove_random_element(nn)
+		n.y = n.y + 1
+
+		local summon = mcl_mobs.spawn(n, "mobs_mc:iron_golem")
+		if summon then
 			minetest.sound_play("mcl_portals_open_end_portal", {pos=n, gain=0.5, max_hear_distance = 16}, true)
-			return minetest.add_entity(vector.offset(n,0,1,0),"mobs_mc:iron_golem")
+			return summon
 		end
 	end
 end
diff --git a/mods/ENTITIES/mobs_mc/villager_evoker.lua b/mods/ENTITIES/mobs_mc/villager_evoker.lua
index 9d465c25d..2dc175341 100644
--- a/mods/ENTITIES/mobs_mc/villager_evoker.lua
+++ b/mods/ENTITIES/mobs_mc/villager_evoker.lua
@@ -55,14 +55,16 @@ mcl_mobs.register_mob("mobs_mc:evoker", {
 		basepos.y = basepos.y + 1
 		for i=1, r do
 			local spawnpos = vector.add(basepos, minetest.yaw_to_dir(pr:next(0,360)))
-			local vex = minetest.add_entity(spawnpos, "mobs_mc:vex")
-			local ent = vex:get_luaentity()
+			local vex = mcl_mobs.spawn(spawnpos, "mobs_mc:vex")
+			if vex then
+				local ent = vex:get_luaentity()
 
-			-- Mark vexes as summoned and start their life clock (they take damage it reaches 0)
-			ent._summoned = true
-			ent._lifetimer = pr:next(33, 108)
+				-- Mark vexes as summoned and start their life clock (they take damage it reaches 0)
+				ent._summoned = true
+				ent._lifetimer = pr:next(33, 108)
 
-			table.insert(spawned_vexes[self],ent)
+				table.insert(spawned_vexes[self],ent)
+			end
 		end
 	end,
 	passive = false,
diff --git a/mods/ENVIRONMENT/lightning/init.lua b/mods/ENVIRONMENT/lightning/init.lua
index 079c9cb38..d4756bd9f 100644
--- a/mods/ENVIRONMENT/lightning/init.lua
+++ b/mods/ENVIRONMENT/lightning/init.lua
@@ -19,7 +19,6 @@ local set_node = minetest.set_node
 local sound_play = minetest.sound_play
 local add_particlespawner = minetest.add_particlespawner
 local after = minetest.after
-local add_entity = minetest.add_entity
 local get_objects_inside_radius = minetest.get_objects_inside_radius
 local get_item_group = minetest.get_item_group
 
@@ -165,7 +164,7 @@ function lightning.strike_func(pos, pos2, objects)
 
 	-- Events caused by the lightning strike: Fire, damage, mob transformations, rare skeleton spawn
 
-	pos2.y = pos2.y + 1/2
+	pos2.y = pos2.y + 1
 	local skeleton_lightning = false
 	if rng:next(1,100) <= 3 then
 		skeleton_lightning = true
@@ -174,14 +173,14 @@ function lightning.strike_func(pos, pos2, objects)
 		if get_node(pos2).name == "air" then
 			-- Low chance for a lightning to spawn skeleton horse + skeletons
 			if skeleton_lightning then
-				add_entity(pos2, "mobs_mc:skeleton_horse")
+				mcl_mobs.spawn(pos2, "mobs_mc:skeleton_horse")
 
 				local angle, posadd
 				angle = math.random() * math.pi * 2
 				for i=1,3 do
 					posadd = { x=math.cos(angle),y=0,z=math.sin(angle) }
 					posadd = vector.normalize(posadd)
-					local mob = add_entity(vector.add(pos2, posadd), "mobs_mc:skeleton")
+					local mob = mcl_mobs.spawn(vector.add(pos2, posadd), "mobs_mc:skeleton")
 					if mob then
 						mob:set_yaw(angle-math.pi/2)
 					end
diff --git a/mods/ITEMS/mcl_mobspawners/init.lua b/mods/ITEMS/mcl_mobspawners/init.lua
index f2ee44ab1..5c934a819 100644
--- a/mods/ITEMS/mcl_mobspawners/init.lua
+++ b/mods/ITEMS/mcl_mobspawners/init.lua
@@ -147,20 +147,14 @@ local function spawn_mobs(pos, elapsed)
 	-- get meta
 	local meta = minetest.get_meta(pos)
 
-	-- get settings
-	local mob = meta:get_string("Mob")
-	local mlig = meta:get_int("MinLight")
-	local xlig = meta:get_int("MaxLight")
-	local num = meta:get_int("MaxMobsInArea")
-	local pla = meta:get_int("PlayerDistance")
-	local yof = meta:get_int("YOffset")
-
 	-- if amount is 0 then do nothing
+	local num = meta:get_int("MaxMobsInArea")
 	if num == 0 then
 		return
 	end
 
 	-- are we spawning a registered mob?
+	local mob = meta:get_string("Mob")
 	if not mcl_mobs.spawning_mobs[mob] then
 		minetest.log("error", "[mcl_mobspawners] Mob Spawner: Mob doesn't exist: "..mob)
 		return
@@ -174,17 +168,14 @@ local function spawn_mobs(pos, elapsed)
 	local timer = minetest.get_node_timer(pos)
 
 	-- spawn mob if player detected and in range
+	local pla = meta:get_int("PlayerDistance")
 	if pla > 0 then
-
 		local in_range = 0
 		local objs = minetest.get_objects_inside_radius(pos, pla)
 
 		for _,oir in pairs(objs) do
-
 			if oir:is_player() then
-
 				in_range = 1
-
 				break
 			end
 		end
@@ -213,7 +204,6 @@ local function spawn_mobs(pos, elapsed)
 
 	-- count mob objects of same type in area
 	for k, obj in ipairs(objs) do
-
 		ent = obj:get_luaentity()
 
 		if ent and ent.name and ent.name == mob then
@@ -228,33 +218,28 @@ local function spawn_mobs(pos, elapsed)
 	end
 
 	-- find air blocks within 8×3×8 nodes of spawner
+	local yof = meta:get_int("YOffset")
 	local air = minetest.find_nodes_in_area(
 		{x = pos.x - 4, y = pos.y - 1 + yof, z = pos.z - 4},
 		{x = pos.x + 4, y = pos.y + 1 + yof, z = pos.z + 4},
 		{"air"})
 
-	-- spawn up to 4 mobs in random air blocks
+	-- spawn mobs in random air blocks. Default max of 4
 	if air then
-		local max = 4
-		if spawn_count_overrides[mob] then
-			max = spawn_count_overrides[mob]
-		end
-		for a=1, max do
-			if #air <= 0 then
-				-- We're out of space! Stop spawning
-				break
-			end
-			local air_index = math.random(#air)
-			local pos2 = air[air_index]
-			local lig = minetest.get_node_light(pos2) or 0
-
-			pos2.y = pos2.y + 0.5
+		local num_to_spawn = spawn_count_overrides[mob] or 4
+		local mlig = meta:get_int("MinLight")
+		local xlig = meta:get_int("MaxLight")
 
+		while #air > 0 do
+			local pos2 = table.remove_random_element(air)
 			-- only if light levels are within range
+			local lig = minetest.get_node_light(pos2) or 0
 			if lig >= mlig and lig <= xlig then
-				minetest.add_entity(pos2, mob)
+				if mcl_mobs.spawn(pos2, mob) then
+					num_to_spawn = num_to_spawn - 1
+					if num_to_spawn == 0 then break end
+				end
 			end
-			table.remove(air, air_index)
 		end
 	end