April 2016 Card Nerf
It was announced on April 20th, 2016 that Master of Disguise would receive a nerf.
- Now only gives a minion Stealth until your next turn.
Quote from BlizzardThe ability of Master of Disguise to grant permanent Stealth has been a design obstacle for a long time, so we are changing Master of Disguise to only grant Stealth until the next turn. This change opens up exciting options for future cards.