Kessobahn was a pureblood Eleint. He was trapped by a group of Tiste Liosan with the help of the four remaining Hounds of Light. Fourteen of the Liosan drank his blood in order to become Soletaken, but the last Liosan to drink his blood, Uhandahl, died tearing out his own throat. Under Kadagar Fant's command, the remaining thirteen (including Fant himself) then veered into their new Soletaken dragon forms and killed Kessobahn by tearing him apart.
It was possible that the same Liosan previously attempted to use the blood of the Eleint Sorrit for the same means, as she was found with a Blackwood spike in her in seemingly similar circumstances yet no other "new" Eleint appeared in the series.