With how powerful we are now the only way there could be a boss without DA or invulnerability would be giving the boss 1,000,000,000,000,000,000,000 hp. This effectively would be no different than DA, but we’d still see our lovely big and juicy red numbers pop up. It isn’t possible to make a boss in Warframe right now unless they start nerfing us, which this community for the most part is strongly against.