The node says ‘’ You are invulnerable for 1 second after using Warcry. ‘’ Notice the wording in this. I got other effects that trigger on ‘’ using ‘’ warcry such a maelstrom stacks, which has similar wording in the skill tree node: ‘’ You now cast maelstrom when you use warcry ‘’. The reason I point this out is because in the following screenshot you can see that I went for totem warcry which does still trigger my maelstrom node but it does not give me any invulnerability when used by my character the first time. I respeced out of the totem and it does not seem like the invulnerability is working in that condition ether. It would be nice if we had a buff that lasted 1 second to tell us we are indeed invulnerable and see the application of said buff in practice but for the moment I believe this node is not working as intended.
You can see the missiles going trough me roughly 0.5 second after or during the animation of using warcry and still damaging my character.