Shar is the Goddess of darkness, loss, and confusion. She originally held domain over the night sky, but Shar desired a domain governing mortal behavior so as to maximize her ability to manipulate mortal souls into her church’s dark embrace. Shar and her son Mask came to an agreement: they would trade Mask’s domain of secrets for Shar’s domain of the night sky.
However Mask tricked Shar and gave her the domain of confusion instead. Shar was enraged and sword revenge, but Mask has remained one step ahead of her. What Mask did with the domain of the night sky is not known, but there is no record of Mask ever using it. Shar learned from this that few weapons are as potent against the gods as trickery.
To regain some of the power she had lost, she murdered a lesser deity of the Underdark named Ibrandul and replaced him with an aspect – a tiny portion of a gods power brought to life. Think Adam and God’s rib. Through this deception Shar was able to regain much more than she had lost to Mask, and Ibrandul’s primative worshipers never knew the difference.
This went on for centuries until Ibrandul was destroyed by Grumbar Gold. Without her cash cow Ibrandul, Shar had to go back to working for every scrap of power she steals instead of just letting it roll in while she slumbers. The rage she felt at this turn of events was terrible to behold and impossible to describe; but what is certain is that she has sworn revenge against Grumbar Gold.