A commune granted by the Virtue of Fortitude.

It heals you for half your health. The drawback is that when you defeat an enemy, you become stunned at 1hp. If you have a bleed effect or you are fighting an opponent, you will likely die. If a tick passes without a negative hp effect then you could survive it. You must be under 40% health to cast it and the commune lasts 24 hours. I used it less frequently than I should have because arranging the exact scenario for it was difficult timing wise.

The help file is a little off as it seems to imply it is keyed to the opponent who triggers it dying. It is not, though the exact trigger wasnt clear. I triggered it a number of times in PK, then defeated evil creatures while it was in the 'kill something and you get stunned' state (it gives you a buff to show it's duration) with no effect. However once I triggered the heal fighting Quarissa's demon, then later killed an NPC demon and was stunned/died on the next round.