He takes DNA samples of the crew and claims he can locate their home planet in his vast DNA database. As payment for this service he wants one of Pilot's arms, after getting it he gives them the crystal that contains the starmaps for Zhaan, Rygel and D'Argo's planets.
When Aeryn Sun comes to him in order to get her DNA sample taken, he injects some of Pilto's DNA into her eye. It turns out that originally Namtar was one of Kornata's lab creatures that got it's intellect increased, however at one point he started to increase his own intellect and finally he increased his size and gave him self other attributes in order to archive perfection, and one of the last abilities he is missing is Pilot's multitasking capabilities.
Kornata helps mix a potion to revert Namtar's genetic changes and by that rendering him harmless.