I have noticed the same thing. Any card that you need to pick a card to discard to burn a card, even a random card, do nothing. They cost mana and provide no positive or negative effect. I also noticed that when you want to draw more cards, the pile won't shuffle and draw more, it just won't draw you any more cards.
On the topic of the card game though I found it a bit under balanced. After toying around with the different full combos I found the best way to farm dust is just easy mode with 3-4 draw cards and the rest stupify. At medium difficulty you aren't getting enough of a bonus from vulnerability at only 1 turn for it to cost 2 mana. You get more damage from just 3 stupify spells. While I get the card compression factor, it just seems like the stats have been taken from STS and slightly tweaked. I think it's perfectly fine to take the ideas, but STS is balanced at exactly where it is after almost a decade of rebalancing. It just feels like the higher mana cost cards do not effect the game enough on the round they are played and almost zero effect on any round after. Some exceptions are like the damage reduction 3 cost spell. But even then it's just tied for taking damage to kill something faster.
Yeah, I share your thoughts. I played on the normal difficulty. And I struggled hard. Like bosses were almost impossible. The card synergies seems nice but as you mentioned, some of them are very hard to actually use, because you just dont have mana. Also, I feel like that best way to get reliable dmg is to have the most basic gear, because it gives you bonus starting mana and more spell slots, which you can fill... But i really like the idea. I played this game maybe more than a year ago when the fights were very much different. And this feels much better, even with the dissbalance problem.