In many card games, eventually the power creep becomes so disgusting that the designers reign everything back with everything new for an expansion (or even for a whole block like MtG has done a few times). Playable cards with interesting effects but they are a touch “expensive” to play when compared with the previous trend of standards.
I cannot remember expansion names since I’ve quit MtG cold turkey years ago because it was an expensive addiction and I had relapsed a few times before finally getting it out of my system for good but the most immediately memorable time this happened in MY experience was the block first featuring Eldrazi. There were more than their fair share of good cards but there were also a LOT of spells and creatures that were silly-expensive in upwards of triple-multicoloured mana costs, EVEN FOR CYCLING (instead of playing the card, pay cycling cost to discard it and draw a card).
Yes, it narrowed down their respective metas to be even more obnoxious because many of those cards were simply unplayable in a competitive environment but given that Hearthstone is a different game altogether with the various restrictions, I feel like a similar concept may not suffer the same fate as more complex card games like MtG if implemented in the more narrow ruleset Hearthstone operates under.
Would the Classic set and other current expansions still undermine the intent to bring power levels of decks to a more reasonable power curve?
Undoubtedly.
However…that is why the developers would need to be creative enough to design mechanics which would JUSTIFY higher mana costs/weaker bodies. Even strong bodies with “over-costed” mana values could be made if there are conditions which need to be met to play other new creatures and/or spells for a payoff.
Currently, there is too much mana-cheating, discover effects, and extremely efficient cards which do an absurd amount for a very forgiving amount of effort to obtain an end result. “Curvestone” has been a part of snowbally mechanics for a long time now when it was one or the other. Yes, you can get unlucky at times but I do not see dead turns on much of anything outside of control-orientated decks or when games run into topdeck issues from lasting longer than expected.
There will always be fast, frenzy damage decks in zoo and face-decks. That is the unfortunate truth of the game but I still don’t believe that even they could have 100% win over the kind of expansion I would want to see in the future. I don’t want games to last to fatigue every time but currently there’s a small part of me that starts to lose hope when I begin to see eye-to-eye on some people’s notions that Blizzard may as well stop printing cards over 5 mana, barring ridiculous end-game visions where healing is no longer a hard-earned board state and you have face hunters auto-conceding to resurrect priest (I have witnessed a shocking amount of this and as much as I hate the hunter class, even I think that’s painful to watch).
My only concerns are, though: given the scaled down version of similar card games that Hearthstone has, what kind of mechanics would be needed to imbedded into the game to justify players to feel compelled to play outside of the current meta demands for success?