Zandroe is the god of greed and is only mentioned in the Covetous Silver Serpent Ring description. Zandroe is a serpent and is perhaps the same race as the primordial serpents. The ring says that Zandroe manifests in the form of a serpent and has serpent servants. This may mean that Zandroe is a god who controls primordial serpents, or perhaps just lesser forms of serpent.
Zandroe is particularly associated with greed, which is typically viewed as a vice. However, the description indicates that Zandroe simply does not let anything go to waste, no matter how it is obtained, implying a dubious nature.
The best version of the Covetous Silver Serpent Ring is dropped by Mytha the Baneful Queen, a creature that has taken the form of a serpent perhaps due to a form of greed (not wanting her lover to leave her despite having feelings for another).