Okay look, it works like this. Exalts are designed to work off active defense. That is, you can have arbitrarily high ratings of toughness or evasiveness or whatever, but only while your mana bar holds out, at which point you are out of magic to power your active defenses and can get murdered by some regular dudes with some big hammers. This is there so that you can kill someone who can achieve arbitrarily high levels of "I can't die". The game is PvP (the antagonists are the same type of thing you are), so you need to be able to do it or there is no game.
You therefore cannot become invincible passively, that would be against the basic design intent. If any means to become invincible passively exist, they are considered to be broken and will be banned if you actively try to use any in an actual game. So the question "Can I become invincible in Exalted" is answered by "No, and if you find out a way to do it regardless, it will promptly be removed".
