Blizzard is killing Hearthstone Classic and replacing it with a new mode called Twist

pcgamer.com:

Hearthstone's history of adding new modes is a mixed one. Battlegrounds has been so successful that it's arguably supplanted the main Standard mode, but Mercenaries was a shuttle crash from start to finish. Classic, which as the name suggests gave players the chance to time warp back to the vanilla version of Hearthstone, was fun at first but with Blizzard opting not to add any expansions, interest dropped off fast. So I wasn't shocked to learn last week, on a call with modes design lead Matt London and features lead Chadd Nervig, that Classic is getting the chop. It will be replaced by a new mode, called Twist, which also looks to leverage old cards in players' collections.

Set to launch in beta later this month as part of patch 26.6, Twist is its own format with a ranked ladder, monthly rewards, and rotating set of rules intended to unlock previously impossible synergies and create new deck-building challenges. The ruleset being used for the Twist beta, which will run through June and July, is being dubbed 'New Age'. When building a New Age deck you will be able to pick cards from the following expansions, with the twist being that no neutrals are allowed. 

By combining sets from eras that weren't previously playable in Standard together, all sorts of new combos become possible. Existing archetypes also threaten to become much more powerful with the addition of cards that weren't in the pool beforehand. For example, the no neutrals rule immediately makes me think of the Pure Paladin archetype, which doesn't use neutrals anyway. Now consider the fact that Ashes of Outland contains the Libram package which can now be run alongside more recent cards like The Countess and Elitist Snob, and you've got something disgustingly