diff --git a/api.lua b/api.lua
index b38fd4b..dbb5051 100644
--- a/api.lua
+++ b/api.lua
@@ -19,7 +19,7 @@ end
 
 mobs = {
 	mod = "redo",
-	version = "20241122",
+	version = "20241127",
 	spawning_mobs = {},
 	translate = S,
 	node_snow = has(minetest.registered_aliases["mapgen_snow"])
@@ -1039,9 +1039,22 @@ function mob_class:do_env_damage()
 	if self.node_damage and nodef.damage_per_second and nodef.damage_per_second ~= 0
 	and nodef.groups.lava == nil and nodef.groups.fire == nil then
 
-		self.health = self.health - nodef.damage_per_second
+		local damage = nodef.damage_per_second
 
-		effect(py, 5, "tnt_smoke.png")
+		-- check for node immunity or special damage
+		for n = 1, #self.immune_to do
+
+			if self.immune_to[n][1] == self.standing_in then
+
+				damage = self.immune_to[n][2] or 0
+
+				break
+			end
+		end
+
+		self.health = self.health - damage
+
+		if damage > 0 then effect(py, 5, "tnt_smoke.png") end
 
 		if self:check_for_death({type = "environment",
 				pos = pos, node = self.standing_in}) then return true end
diff --git a/api.txt b/api.txt
index 4a26824..11699ea 100644
--- a/api.txt
+++ b/api.txt
@@ -85,8 +85,6 @@ functions needed for the mob to work properly which contains the following:
    'fire_damage'   holds the damage per second inflicted to mobs when standing
    'node_damage'   True by default, will harm mobs when inside damage_per_second
                    nodes.
-                   in fire.
-
    'light_damage'  holds the damage per second inflicted to mobs when light
                    level is between the min and max values below
    'light_damage_min' minimum light value when mob is affected (default: 14)
@@ -178,6 +176,9 @@ functions needed for the mob to work properly which contains the following:
       {"default:gold_lump", -10} -- heals by 10 health points.
       {"default:coal_block", 20} -- 20 damage when hit on head with coal blocks.
       {"all"} -- stops all weapons causing damage apart from those on list.
+                         nodes can also be added so that node_per_second damage
+                         does not affect the mob either e.g.
+      {"ethereal:crystal_spike", 0} -- causes no damage.
 
    'makes_footstep_sound' when true you can hear mobs walking.
    'sounds'               this is a table with sounds of the mob