Zimberfizz was the imp minion of Nomad. He used to be found in the Soul Wars lobby and appears during the tutorial. He is also the starting point for the Grandmaster Quest, Nomad's Requiem. You can exchange Zeal points with Zimberfizz.
During the tutorial, after the player has been killed by Nomad, they can return to the soul obelisk and have a conversation with Zimberfizz. It is revealed that Nomad has a high Hunter level (at least 71) as he had caught Zimberfizz via magic box. Nomad also actually built the soul obelisk, as Zimberfizz states that he had to carry the materials to the site. It is also revealed that Nomad "certainly knows his way around slayer monsters, too".
Zimberfizz is killed during investigation of Nomad's throne room at the beginning of Nomad's Elegy, and may be replaced by either Zanik or Zimberfizz ashes, depending upon player choice during the quest, upon completion of the quest.
In the Chaos Elemental's 13th letter, in Postbag from the Hedge 41, there is a paper which has "Hardens South" written on it. That is an anagram for "Use Shorthand" and the text appears to be written in Teeline Shorthand. The translation is "Uv b wd abt Sl Ws. Nmd is tb frd." Transcribed it says, "You've been warned about Soul Wars. Nomad is to be feared." This makes sense since in the included postbag, we are told that Nomad knows where the souls go and Zimberfizz says "I can see it on his mug." Along with the other clues, it seems that Nomad could be eating the souls or storing them for his evil scheme. The cryptic note in the suitcase confirms this.
Before the release of Nomad's Requiem, Nomad would kill Zimberfizz every five seconds or so. Zimberfizz would reappear moments later, saying something like "I hate it when he does that!". Zimberfizz could also be attacked by players.
Zimberfizz could be found at the 2011 Christmas event after you completed it. He mentions that he is on business.