So, a guy in my group is rather skilled at powergaming, and he once shared an idea to be immune to damage. I made this build as a variation on that.

race: half-dragon human (acid or fire)

wu jen 6/renegade mastermaker 10/warforged juggernaut 2

feats:
H: toughness
1: troll-blooded
3: craft wondrous item
6: craft magic arms and armor
9: <open slot>
12: power attack
15: improved bull rush
*B: adamantine body
18: <open slot>

Kinda convoluted to get there, but the idea is that troll-blooded grants regeneration. I'm not sure of the exact wording, but i'm pretty sure all damage except for fire and acid are converted to non-lethal. Half-dragon grants immunity to one, immunity to the other can be obtained easily via other means (such as a spell). That means that all other sources of damage are converted to non-lethal. The capstone of renegade mastermaker allows the build to qualify for warforged juggernaut--the second level of which grants immunity to non-lethal damage. All damage dealt to you is converted to non-lethal, which you are now immune to. Congratulations. You are now immune to damage.

I chose Wu Jen for the base class so you can clone yourself via Body outside Body and be a small nigh-unkillable army unto yourself.

some other random immunities granted by this build:
criticals
poison
sleep
paralysis
disease
nausea
fatigue
exhaustion
energy drain

comments?