Enable alpha for mobs

mods/ENTITIES/mcl_mobs/api.lua

@@ -3712,6 +3712,7 @@ end
 
 minetest.register_entity(name, {
 
+	use_texture_alpha = true,
 	stepheight = def.stepheight or 0.6,
 	name = name,
 	type = def.type,

mods/ENTITIES/mobs_mc/slime+magma_cube.lua

@@ -78,6 +78,9 @@ local slime_big = {
 		attack = "green_slime_attack",
 		distance = 16,
 	},
+	do_custom = function(self)
+		ice_texture_alpha = minetest.features.object_use_texture_alpha and "blend" or true
+	end,
 	damage = 4,
 	reach = 3,
 	armor = 100,