At the Permanent Transient, there are three Sumat Pols, each identical to each other. They say that there could be many Sumat Pols across the Timescape, each a different race, though no one knows whether that is true or not.
For a treant, Sumat Pol is short - only twelve feet tall - but compared to his humanoid customers he is incredibly tall. Sumat Pol spoke slowly but is kind, jovial, and professional.
Sumat Pol is an incredibly powerful sage, capable of collecting and creating such rare magical items. When Odie attempts to steal from the shop, without looking at the invisible imp a Sumat Pol grabs and eats the imp with little to no effort.
How there came to be three Sumat Pols is currently unknown, they often explain to one another that they do not belong to the same "vector" anymore.
“Angel's Report” (Episode 14)
When the Chain of Acheron completed the Underdark Job, they were granted temporary access to the Permanent Transient thanks to Reginald Orpheo. The officers are greeted by three treants called Sumat Pol and begin shopping.
Behind the Scenes
Sumat Pol, as well as his shop, is a reference to Matt Mercer's Firbolg non-player character Pumat Sol. While there are some differences between the two, for instance, there is a "Prime" Pumat Sol, the personality and abilities of the two characters are incredibly similar.