Alchemist Pestlezugg is a level 45 alchemy vendor located at Gadgetzan in the contested territory of Tanaris. This renowned alchemist sells all kinds of formulas to the better sort of alchemist for a price, because he still is a goblin.
He is also worried about the presence of silithid around Tanaris and Un'Goro Crater. After finding out what the danger was, he became an opponent of the silithid, ready for a fight with poisons and gases.
See List of Tanaris NPCs.