He built the foundations of the Brotherhood of Gralnak in Elysium, and was granted power by his demonic master, living to an unnaturally high age, and then having his soul claimed by Gralnak before it could pass through the Court of Judgement and be claimed by one of the pantheon of the time.
In Hades Nishgar continued to serve at Gralnak's side, helping to stabilise and strengthen Gralnak's following there amongst the other demons, and later serving a similar role of leadership once Gralnak ascended and moved much of his focus to the Plane of Elysium.
Over the centuries since his death, the soul of Nishgar has interacted with Elysium numerous times through the actions of both mortal and demonic necromancers, with particular note being his contributions to the religious text of the Gralnakian Brotherhood, The Book of Gralnak.
In 1557 Nishgar's most recent foray into Elysium came, with his manifesting a more physical presence than normal, using an artifact named the Nishgarnet which was brought into Elysium by the Gralnakian champion Cruvian. Though Cruvian was slain by the mortals Andrew Sephyre and Pewter the Pirate, the Nishgarnet eventually fell into the hands of Makkar, Emperor of Vagla, who used it to summon Nishgar in a crystalline form to wreak havoc on the enemies of Gralnak. Eventually the gem was recaptured by the order of Zharadan, and destroyed by Rillion, Cloudi and Saul. This caused the ghost of Nisghar to be released in an ethereal form in which he proved almost undefeatable by the mortal forces of Elysium, but Gralnak eventually withdrew him back to Hades to resume his leadership of the demonic hordes.