Modal (Choose One) effects - I guess this would be neat, even though I’m not a particular fan of the mechanic and I don’t find it overly interesting. What I do like about it is some of it’s flavor, for example going balls deep and Uprooting Ancient of War in HS.
Multifaction cards - Same, I don’t see the need for them to exist in a game where there are already factions and neutral cards. I don’t even know why HS team decided to put them in their game. It’s just makes things complicated and and I fail to see how it improves the current system.
Activated Abilities - these sound good, even though I’d like to see some real examples of said cards to get the better understanding of them and as such see how would they fit duelyst.
Playing on the Opponent’s Turn - I agree with you here. Secrets and similar triggers that only happen on your opponents turn is the furthest the game can go in that regard. But that being said, fuck secrets. If CPG decides to implement something like this it better not be fucking secrets. It’s such an awful and infuriating game mechanic which is more than often about guessing than about being skilled and playing around it.
Hand disruption - I’m okay with this, as long as it’s not something stupid like removing cards from the enemy hand, basically 90% of this thread.
I don’t have lots of mechanics which I would like to see, but one of them is controlled discard mechanic which applies only to your own action bar. I like mechanics that have some kind of drawback in general. Maybe a mechanic where you pay life in addition to minion’s mana cost in order to play minions with certain stats earlier than one normally would, I’m sure it’s been done before.