Hot cobble hurts.

README.md

@@ -2,7 +2,7 @@
 
 Fun Caves started as an attempt to convert the mapgen V6 caves into a lua mod, so they could be used with any mapgen. However, I've since turned it into an all cave environment, with no surface at all.
 
-Players spawn into a massive cave, hopefully in an area with mushrooms, and start digging. Dig up, dig down, dig sideways, you'll never find a surface world -- no trees, no flowers, not cows and horses. What you will find are fungi, algae, monsters, and lots and lots of goblins. Every ore is available, everywhere, which means there's a lot of it.
+Players spawn into a massive cave, hopefully in an area with mushrooms, and start digging. Dig up, dig down, dig sideways, you'll never find a surface world -- no trees, no flowers, no cows and horses. What you will find are fungi, algae, monsters, and lots and lots of goblins. Every ore is available, everywhere, which means there's a lot of it.
 
 Hint: Find some giant mushrooms, first thing. They're handy.
 

nodes.lua

@@ -419,6 +419,24 @@ minetest.register_node("fun_caves:hot_cobble", {
 	}),
 })
 
+minetest.register_abm({
+	nodenames = {"group:hot"},
+	interval = 2,
+	chance = 1,
+	action = function(pos, node, active_object_count, active_object_count_wider)
+		for _,object in ipairs(minetest.env:get_objects_inside_radius(pos, 0.95)) do
+			if not minetest.registered_nodes[node.name] then
+				return
+			end
+			local dps = minetest.registered_nodes[node.name]["damage_per_second"]
+			if object.set_hp and object.get_hp and dps then
+				--print("damage. "..object:get_hp().." hit points left")
+				object:set_hp(object:get_hp() - dps)
+			end
+		end
+	end})
+
+
 -- mushroom growth
 minetest.register_abm({
 	nodenames = {"flowers:mushroom_brown", "flowers:mushroom_red"},