Hearthstone Mercenaries: Mysterious Stranger Appearance Rate Changes
Blizzard just nerfed the most reliable way to get Tasks for your Mercenaries, which was the easiest way to gain their most powerful Equipment and the Coins needed to upgrade them. Progress on these things will no doubt slow down considerably. This change should already be live.
Quote from BlizzardWe are adjusting the appearance rate of Mysterious Stangers to be based on the relative level of the strongest Mercenary in your party compared to the suggested level of the Bounty. This move is to encourage people towards more engaging gameplay instead of repeatedly taking on low-level Heroic Bounties with highly over-leveled Parties.