Naska is a dwarf with a crossbow attached to the stump where his left hand once was. An agent of the Zhentarim, he met the heroes at ChairCon in Waterdeep . Evelyn converted him to the worship of Lathander. He seems to have a bit of a crush on her. 
The group eventually realized that Naska was secretly living in the basement of their home. Naska clearly had a crush on Evelyn. Paultin humiliated him by trying to charge him 20 gp per month rent and holding a gold coin above his head, daring the dwarf to take it. Naska shot Paultin with his crossbow and was banished. It is believed that he returned later and stole Waffles for the Xanathar.  When the group's manor was attacked, Naska was among the assailants. He was on the fence about attacking, and Evelyn got him to feed the group information. 
Naska's severed head was sent to the group in a coffin. It emitted gas spores that transformed into baseball-sized beholders.