FWIW, Wikipedia:
Tamas is also a Guna http://en.wikipedia.org/wiki/Guna or Quality that is much needed to counter Evil, as an example Bhairava http://en.wikipedia.org/wiki/Bhairava Incarnation of Lord Shiva http://en.wikipedia.org/wiki/Lord_Shiva is a Tamasic Avatar, and Lord Shiva Himself out of the Trinity represents Tamas http://en.wikipedia.org/wiki/Tamas, where Shiva drinks the poison of his devotees to get rid of their sin, hence absorbing the Tamo-Guna of devotees, in Devi http://en.wikipedia.org/wiki/Devi worship, there are many goddesses which incarnate within the Shakta http://en.wikipedia.org/wiki/Shakta sect of Hindusim where goddess are offered animal sacrifice.
