mods/ENTITIES/mobs_mc/5_spawn_abm_check.lua

@@ -1,11 +1,20 @@
+local function is_forbidden_node(pos, node)
+	node = node or minetest.get_node(pos)
+	return minetest.get_item_group(node.name, "stair") > 0 or minetest.get_item_group(node.name, "slab") > 0 or minetest.get_item_group(node.name, "carpet") > 0
+end
+
 function mobs:spawn_abm_check(pos, node, name)
 	-- Don't spawn monsters on mycelium
 	if (node.name == "mcl_core:mycelium" or node.name == "mcl_core:mycelium_snow") and minetest.registered_entities[name].type == "monster" then
 		return true
+    --Don't Spawn mobs on stairs, slabs, or carpets
+	elseif is_forbidden_node(pos, node) or is_forbidden_node(vector.add(pos, vector.new(0, 1, 0))) then
+		return true
 	-- Spawn on opaque or liquid nodes
 	elseif minetest.get_item_group(node.name, "opaque") ~= 0 or minetest.registered_nodes[node.name].liquidtype ~= "none" then
 		return false
 	end
+
 	-- Reject everything else
 	return true
 end