it seems a bit too random.
This basic argument has come up multiple times, in various different flavors.
Myth is not...I repeat NOT
about predictability. You can see this from the random nature of the card drawing with both the boss deck as well as the hero action decks. This creates variable gameplay. This is one of the marketable
features of this game.
If you are looking for a game where you always know what to expect, there are plenty of other options out there. If you find the variable, unpredictable nature of Myth is exciting...then go for it.
In cooperative games I've played you usually know what you should aim for and do
This is no different in Myth. You are given your goals. The exciting thing, however, is that the journey taken to accomplish that goal is less predictable than comparable games.