Gamehelp: Dungeon Siege 3 - Enduring Champion achievement

100.000 damage taken is quite a bit, especially in one session. Meaning in one go. If you save and reload, the internal counter is reset.
I was doing this on my Hardcore play-through and was really aiming to get all the deed modifiers to help me out. Sustaining 100k damage will net you the Enduring Champion deed which gains you +2 stamina, or +20 hit-points.

Enduring Champion (10) Survive 100,000 points of damage in one adventure - but ideally not in one hit.

The easiest place I found for this is in Stonebridge, more specifically the Crypts of the Sacred Blood. A few minutes in, you’ll come across a second automatic bridge that has to be extended, right after a convenient save-point. When you close in on this bridge it will show you a short sequence of giant pendulum blades lowering from the ceiling. Clear the bridge of enemies and note the locked door at the end; this will ensure peace and quiet while you die some 100-150 times. Position yourself close enough to one of the blades so you take damage, but not as close that you fall over beneath it. Make sure your follower is behind you and not off to the side.

The blades did about 150-160 damage each swing, roughly every second. My character had 1500 hit-points and was resurrected on the money every time, with 750 hit-points. This was the perfect set-up and I just left the game alone and went on to do something else in the meantime.