Immune can get out of hand but currently they aren't so bad. Artifacts are the real problem. What exactly do you mean by timer? The artifacts effect goes off when it hits zero?TBH, I don't mind special cards/unitless decks if I almost never see them. Logically, the tactic should not be strong and not viable, it should almost be an automatic-lose kind of deck. If it was, very few people would play it at all, and if that would be the case, problem would be solved at least for me, since I don't mind the deck itself, I just mind seeing it/playing it.
If there was a rare and weak special card deck I would have to play once in awhile, I would not really mind so much, especially if I knew that it is so weak that I must win against it.
I don't have a problem with Scorch cards, only in the context of special cards decks, because those scorch cards are in my experience core to their tactic. Regarding predatory dive, I think the purpose behind it is to actually destroy one unit on each side, not just scorch a unit on the other side. Now it is used as a no-unit deck scorch card, and it is used as a round starting scorch card in more legitimate decks, and i don't think that was the intention behind the card. I think the purpose was for it to be a card used with the deathwish ability. Both cards die, but deathwish is triggered.
I think they could safely remove the new "mini-scorch" card they added in Crimson Curse. And I think the 9 provision epidemic card can be a gold card instead of a bronze. Predatory dive could be adjusted to work as the design behind it intended.
You think unitless decks are out of control due to artifacts, I think it is out of control due to scorch like cards. Perhaps it is one or the other, or perhaps it's both or either. Anyways, as I said somewhere else to you, if they need to adjust some artifacts to avoid filling the board with those, they can add a use timer on some of them. This would make it more tactical and strategical when you would place them etc too and avoid filling the board with them with no purpose.
You can't just expect to have a board full of artifacts and enemy units. Why would the enemy units then not destroy them? Ergo, the timer.
Also, personally I like that a few units can have immune, I almost never use it myself, and those units are not overpowered, especially now that they fixed Saesenthessis. But I think it's bad that they can manually be targeted while on hand, and this is also problematic in relation to the special cards deck. What's your thought on immune in this regard?