Slicker Silvertongue is a character in Might and Magic VI: The Mandate of Heaven. He is Wilbur Humphrey's representative on the High Council of Enroth, and can be found in the council's headquarters in Freehaven. He is also secretly a member of the Temple of Baa.
The party attempted to secure Wilbur Humprehy's vote on the council by completing the Find Lord Kilburn's Shield quest. But when the council voted, Slicker Silvertongue went against his master's wishes and denied the party access to the Oracle of Enroth.
Wilbur believed that Silvertongue had become delusional after spending so much time investigating the Temple of Baa, or that the Temple had placed a mind-control spell on him. He asked the party to travel to the Superior Temple of Baa and find a cure for him.
The party found a letter from Zenofex, leader of the kreegans, to Slivertongue, asking him to prevent the party from gaining access to the oracle - even if doing this exposed him as a traitor. When Silvertongue was presented with evidence of his disloyalty, he fled from the council, and the party was granted admission to the oracle.