Any Idea.

/pause allows you to go invincible until you unpause. maybe there is some way to stay paused forever and run around? That would be great for rushing in dungeons! No hate, just a suggestion.

is there anyway to exploit the 5 seconds or so grace period when you start dungeons?? like when u first enter and the monsters dont react to you at all

No. This action is done completely by the server (probably using the same code rogues use with their invis ability).