According to the forums, if I use rebirth (the one that costs the most) I should lose 10% heroism but instead I lost 50%. This happened twice on my main Rogue Feline.

I'm going to get the heroism back eventually though :).

EDIT: Resurrect drops all heroism instead of 50%...

The bug is that the ressurrection system is still using the penalties that it applied during early closed beta, it never switched over to the new penalties that were introduced near the end and still hasn't been.

Be sure to /bug this ingame.