The last update for the Hearthstone Mercenaries will be released in version 25.4, putting an end to new content for the single-player mode. However, no additional content will be added as Blizzard intends to make the Hearthstone and Battlegrounds modes the best they can be.
Version 25.4 adds six new mercenaries, faction banners, and end-game boss rush content. Several existing mercenaries will gain a second type, allowing for a variety of new synergies across your teams and bringing Mercenaries in line with the other game modes.
The main content enhancement to this update is the Mythic Boss Rush end-game mechanic, which offers challenging bosses with randomised elements. This takes the existing bounty system and simplifies it for high-skill gameplay, and allows you to enhance your mercs' abilities, equipment, and treasures beyond the usual limits.
The Mythic Boss Rush is a free update to the Travel Point and is available once you have completed Heroic Bounties and had at least one maxed mercenary.
The Hearthstone Mercenaries' last update has all you need to know about them. If you're looking for a new CCG to play, check out our Marvel Snap decks guide.