I'd say exciting as its an interresting way to give spells a different way of being powerful. Echo was cool, but the effects / stats had to be below average for it to be fair. With twinspell they'll have more freedom to make more above average power cards.
I'll assume that the devs are taking the power + duplication payoff into account, but who knows we might get another ultimate infestation power card.
I feel like the only great Twinspell will be if someone gets a really nice, expensive board clear with Twinspell. Something powerful enough to guarantee the board clears, but also something you wouldn't play twice in a turn anyway. Or maybe something that could be played twice in a turn if needed, so basically giving you the option to pay double for double the damage or wait and just have an extra copy.
The Treant spell costs way too much to work in a Token/Treant Druid. It's 8 mana for 10/10 in stats, sure, but spread out into 5 2/2 minions. I guess it'd be good to force your opponent to use all their board clears while not running out of refill for the board?!? Maybe I'm wrong and the 8 mana 5 2/2 Twinspell will be great. In fact, I hope I am! I've quietly played some Treant Token Druid in Casual mode from time to time and would love to see it get stronger!
I suppose that any mechanic is only as strong as the cards that are supported by it. For example, I think Inspire had the potential to have some super strong cards, but I think that it was slightly let down for the most part.
If all the Twinspell cards are like the druid one (which I don't think is that strong - though it's not terrible either) then it might be a fairly benign mechanic. We will have to wait and see. :)
I think its ok, but an expansion called rise of shadows could have graveyard interaction mechanic as well. Imagen a mechanic where attack/hp are dependent on number of played cards (cards in graveyard). But this is OT. :D
Twinspell: You get a copy of the spell when it’s played
I can't decide which leg to stand on. It could be too powerful, but on the other hand it could bring some fun combos and it lets you effectively have 4 copies of a spell.
Right now I am leaning towards excited.
If all the cards are akin to The Forest's Aid in terms of power level, then I think it would be fine. Especially since The Forest's Aid would really only be played in a token style deck. If the other Twinspell cards happened to be universally good (such as Fireball or Hellfire then I think they'd teeter toward the too good side.
Discover -> Similar to Tracking even if slightly different.
Recruit and magnetic probably have something similar too since it's not that original so yeah, I think adapt and quest are the only real new keywords in the game. Un'goro, what a great time, miss it :'(
Lifesteal was the one I was forgetting! That keyword totally changes the game. I would say in a bad way. I think obsidian statue was released before lifesteal. Could be wrong.
twinspell might be the laziest attempt at a new mechanic yet. you can tell they came up with it at the same time as echo. I can just hear it being brought up in a meeting “hey echo only works on 5 mana or less, what if we did it with more expensive cards?” “OMG 2 mechanics for 1! Genius!” “My work is done here, gonna take the next 4 months off!”
Fun fact about Twinspell: Eternal TCG has a similar mechanic except you get the second copy when you draw or generate the keyword card, rather than on cast. This has led to some meme decks where you stick your Twinspell card to the top of your deck constantly for infinite value/burn/bombs. This hasn't broken the game yet. HS's version has a lot less abuse potential, so there's no need to worry