Gaunter O'Dimm is the star of Gwent's Master Mirror expansion

Gwent’s next major expansion releases on June 30, and one of The Witcher 3’s most enigmatic villains plays the starring role. Gaunter O’Dimm, the powerful grifter from the Heart of Stone expansion, features heavily in the appropriately titled Master Mirror expansion.

The pack includes over 70 new cards, some of which are exclusive to certain factions. New evolving cards will be introduced to the game, and these will grow more powerful with each round. It appears there will be six of these cards, with the first set to be revealed on June 6.

source: gamezpot.com